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rosco01

Lc Lj Torana Scratch Builds

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Ok folk,

back with a short report on the left hand knife tool...

Bugga!.... I might have to make a right hand one as well..... the left hand tool works a treat... it is razor sharp and leaves a very smooth finish, even when making cuts at right angles to the work.

To make smooth cuts normally, the cutting tool is turned so that it is almost "rubbing" onto the surface of the work, taking fine cuts at slower speeds has always produced fine finishes for me... but, this new tool has rewarded me with very good finish even before I turn it towards its side edge..

 

I have made one huge mistake (again)... as I did with wheel #1.... I did not tap the drilled grub screw hole before turning down the hub.... this makes fitting the tap difficult to get going.. I managed with wheel #1.. but it demanded that I use the Dremel with a diamond grinding bit in it to open up the semi hole of the rim... such will be the case with this wheel #5..... too eager to use the knife tool, I'm afraid...

 

We have not reached the final size of the hub yet.. but the step and left side rim are down to 14.33 mm and 12.5 mm respectively.. exactly what I wanted them at.. the hub is to width - 1.63 mm.. but not yet down to 6.5 mm in diameter.. I am also yet to turn down the right hand rim... 12.5 mm again.

 

Pic....

 

01-lh-knife-cuts-amil.jpg

 

 

Ok, rather than end it here... I'll add a little bit more to the lathe description...

 

The "ways".. on which the saddle (or carriage) runs along are very easily damaged... especially around the area most used on them... that being, under the chuck.

"Things" often drop out from the chuck when loosening or tightening a work piece in it..... and it is even known for the lathe to be set into motion with the chuck key still in it.... both of which cause permanent damage to these "ways"....

Look at any lathe - and you can tell what sort of respect it has been given by the operator... in almost all cases, you will see "marks" on the bed in the area of the chuck....

One little mark may not affect the accuracy or wearing of the lathe... but, as these marks continue.. so too does the accuracy suffer.. and they also cause more and more wear to the dovetail shape of the carriage... and "gib strips"... (inserts which are adjustable so that there is minimal lateral movement in the carriage).

 

This is my lathe bed... if you look closely, you can see very fine marks on the far bed just up near the chuck... these were done early in the life of this lathe... and I have to put my hand up for them....

Fortunately, they are not in a location that the carriage reaches in use... but, they are marks all the same.

There are absolutely no other marks on my lathe bed or the cross-slide or compound slide "ways"..Pic..

 

02-lathe-bd-mail.jpg

 

Early on, on recommendation from the author of my most prized book on lathes, I built a wooden bed protector... as seen here..

 

03-lathe-bed-protector-mail.jpg

 

I am very disciplined that I fit this cover over the bed whenever I am adjusting or messing around with anything in the chuck... it is a very simple process of sliding the wooden cover in and over the bed... takes less than two seconds... in or out...... and, if you look at this ingenious contraption... you'll notice marks in it... those are all "saves" from the precious lathe bed....

 

Ok, that's it for tonight... I should have #5 wheel well and truly done tomorrow... maybe even #6 as well.. and we'll only have two more wheels to go for both models....

 

frats,

Rosco

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Hi folk,

update...

 

#5 wheel was turned yesterday... everything identical to previous four.. but, axle hole off centre - had me stumped.

I considered it may have been the pilot drill bit not being centred properly in the tailstock drill chuck.... dirt, swarf... anything... It's off centre by about 0.5mm and it annoys the daylights out of me... I love true running wheels.. both in a centre line, and also vertically centre..... this wheel is out 0.5 mm in both...

 

Today, I turned #6 wheel.... again, my turning is almost perfect. I checked and checked the pilot drill bit and it "seemed" to go easily into the hole made by the small drill centre.... ran it through and all seemed fine this time..... ran the 2.38 mm drill bit through and again, it has gone off centre... same drill bit used for first 5 wheels...

 

I have done a lot of reading tonight - it seems, the tailstock can often go out of adjustment..

 

I made up a "test bar" not long after setting the lathe up..... have not used it since.... tomorrow, will be a day of checking the lathe for why it is now drilling off centre.

 

I checked the drill bit.. it has equal flutes on the end of it.. it is not bent nor can I see any reason why aluminium would damage the HSS... the only use this Suttons HSS drill bit has been used for is on these 6 wheels...

 

We'll know more tomorrow...

 

On a brighter note - I spent a few hours last night on the body... I have re-profiled the door quarter vent windows, door main window and rear side windows... and cleaned up a lot of the casting profile excess.... see what you think...

 

01-windows-profiled-mail.jpg

 

before -

 

02-unprofiled-mail.jpg

 

 

I have a lot to do yet... I am currently considering removing the quater vent post and fitting a brass rod, filed flat on the outside. I would do this for strength only.... an errant thumb/finger might just crush this now very thin post....

 

I'm not in love with the rear spoiler.. I need to study pix to get this right - it appears too large and the rear rakes back too much from what I can see. I remember fitting one of these to my cousin's LJ in 1972.... from memory, the rear was almost vertical..... will take a very close look at all the pix I have of the LJ XU-1 and profile accordingly.

 

I have now decided I am going to remove the cast grille.. and make my own in brass... I like "open" vents... the grille is a must for me...

I will also open the three slot vents in the front guards.. and the front air dam intake below the bumper.

 

I'm not sure that I'll be brave enough to attempt the cowl intake vents... they are very fine... I might just "slot" them deeper and when paint is added, go over the vents with a "wash"... this is a watered down black/grime/grey paint applied then rubbed off..... it creates great detail to areas such as this..

 

Further, this car will not be "showroom" painted.. it will have very feint "use" weathering on it... a very slight "tinge" of tyre and brake dust rearwards of each wheel... but, the rest will be highly cut and polished.

I do like to bring life into a model.. "weathering" for me, is just as big a part of detailing as is the fitting of extra detailed parts... in a photograph, it is often the missing link between visual depiction of it being a model and a pic of the full sized car..... probably 3 months or more before we get that far into the build... I have to learn to build a chassis yet....

 

So folk, we stalled today - lathe issues... will have a report with pix tomorrow.... hoping #7 wheel will run true...

 

frats,

Rosco

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I'll more than likely drill the 3/32" axle hole before boring the open end tomorrow.. and drill through into wheel #2 as well.... negates the need to centre drill the next one..

 

 

 

Hi Rosco

Great tutorial you have going on here. I hope you are enjoying the trials and tribulations of making rims.

 

 

Using the above method to centre is not an accurate one. As you have move along the stock from one rim to the next, you move away from your original centre at the start of your first rim. Considering your now on your 5th and 6th rims and assuming each rim requires something like 15mm of stock including the parting off, the centering for your 5th rim is now in the order of 60mm along from your original centre and using a drill to centre. Stock doesnt hold your drill straight in this process. This drill is narrow, relatively speaking, anything over 3 x the diameter of a drill bit is considered a long drill hole. So very difficult to maintain absolute concentricity ! Each wheel is most probably slightly out but not obviously so it hard to detect until the 5th or 6th one is compared to the 1st, which was centred accurately.

 

I find turning and boring the rim out first before I drill, leaving with about 3.5-4mm left to drill gives me most consistent results. and centre each rim with a centering drill. I also use a .0935 (#42) drill for drilling slot It and most other axles usually. It gives the desired tolerance fit, 3/32 gives a clearance fit, it tends to pull the rim of the axle centre when snug up with the grub screw

NSR axles I use a .0925 drill bit, they are slightly smaller for some reason.

the best results I find are when I actually bore the axle after pre centering then drilling using a 2.3mm bit then bore it. My boring bit is very small, a ground down broken 4mm drill bit in a square sleeve mounted to the compound. very time consuming but worth the effort.

 

Keep up the good fight

Cheers


"Me Auntie's a Jack !!!"

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Thanks heaps, Slo1quick - took me two reads to digest what you explained - but I get it now... and yes, I can very well see that by using a previously drilled centre to start a following wheel - it progressively goes off centre... I have got to #5 and it has shown up at 0.5mm....... so, it's probably gone off centre by 0.1mm in the last couple of wheels... however #1 - #4 run true....

 

Further, I appreciate that it is imperative to gain a tolerance ft... the grub screw would indeed push the axle away from true centre with any clearance made in the bore.... with wheels #1 - 3, I was able to effect a very close clearance fit... I used a diamond stone to hone down a 3/32 drill bit.... with wheel #4 - for some unknown reason, I could not fit the axle into the bore made using this bit.. maybe it was because the centering previous hole had offset it and my drill bit went in on a slight angle as it tried to straighten out the flex in the bit.....

I hand reamed it using the 3/32 in a pin vice.....

 

#5 has become the problem child.. and I believe I drilled it through before boring out the insert recess..... didn't write down notes on that wheel.... and, as it always seems to be with my practices... for the discipline I take in making notes - if I am going to run into trouble, it will be after I haven't...

I have a small clipboard (1/2 A4 Size) and it lays on the workbench with a pencil always on it...... paper is cheap, cutting sheets of A4 into half affords a thick pad of note paper...

 

I fully appreciate now why to drill the axle hole last.... and pre centre it with a centre drill.. then pre-drill and finally run through with the 3/32... I will chase down the recommended drill bit you suggest.. I am using a Suttons HSS bit - up until now, I have had great success with Suttons tools... but, if I can gain further accuracy - I will most certainly follow your lead.... can you recommend/suggest a source for purchase please.....

 

I am going to none-the-less check the tail stock... I now have to..... I will fit the live centre into the Morse mandrel bore and the dead centre in to the tailstock Morse quill then fit my 12" test bar and test dial indicator... take readings along the bar both horizontal and also vertical.... any mis-alignment should show up.

I had not considered that the drill chuck jaws might be out.. having produced four wheels were run true.... but, I'll check those as well.

 

I have plenty of "broken" drill bits - I am certain I can find a 4 mm.... can you explain a bit more in detail the method to make such a tool... angle of the bit etc...

It took me a second read, but I understand you fit this into a square sleeve and mount it in the tool post.....

Do you then use this to bore your axle? or are you using it to bore the internal rim?.

 

Boring the axle with it makes sense, we do our perfect turning using cutting tools in the tool post, why then would we not use the same reference to centre drill.... however, it conflicts with your making mention of using the #42 drill. Either way - great info, thanks - my eyes are opening to new considerations for working the lathe...

 

I had considered drilling the axle hole using the Mill if couldn't get the drill bit to stay centred using the tailstock.... but, there would be other critical errors to be factored in... the wheel not being placed absolutely flat on the bed being the most critical... and accurately positioning the drill bit exactly centre ..... I'll stick it out with the lathe until I have exhausted all options...

 

Again, thank you for this great information you freely forward.. it is very much appreciated.

 

frats,

Rosco

Edited by rosco01

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Fascinating reading about the on going process with producing these wheels.

As mentioned earlier, if you just showed the finished product it would just be "Meh, just a set of wheels, so what?"

Great look at what goes on "behind the scenes"

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Ok folk.... no "machining" done today.... this thread is turning (excuse pun) into more of a lathe thread than a scratch build one.. we'll be on the move with the LJ thread again soon... I just had to find this issue with the lathe - it was doing my head in.....

 

Ok - 11 pix.... what a day! Learned an awful lot more about my lathe.....and the quality of Chinese machines...

No big issue - basically the lathe is extremely accurate.. but, some of the workmanship leaves a bit to be desired...

 

To start tonight's session, I wasted nearly an hour this morning searching for my dead centre..... pulled the entire contents of both the lathe and mill cabinets apart... and the set of metal drawers.... overlooked it the first time around - wasn't looking for the tool itself, rather than the little plastic box it came in.... nope - it was wrapped up in calico and protected by chain oil.... forest and trees syndrome...

 

Before I set to the tailstock, I checked any bearing slack or end float in the mandrel end, fitted a test piece and checked run-out of the chuck... all good..

 

I set up the test bar between the dead centre in the tail-stock and a woodworking centre in the mandrel (tapered hole in the shaft at the drive end). ((Note to self - I really need to purchase an MT 3 dead centre for the mandrel end))

 

Set up my dial test indicator... and ran the length of the bar...... it was out - phew!.. so I'm hoping we don't need to go looking elsewhere when I finally get to turn some more wheels....

 

Ok - here it goes...

In the pic below, you can see the test bar set up into the dead centre fitted in the quill of the tailstock. The test dial indicator has been mounted to the traveling saddle and I have "zero'd" it to 0.00.....pic

 

001-test-bar-tailstock-end-mail.jpg

 

We now run the saddle back towards the chuck end of the lathe.... the indicator reads out any variation from the zero reference at the tailstock end..

In the pic below, you can see that the indicator has gone 0.14 mm negative... revealing that the centre line of the quil in the tailstock is out of alignment with that of the mandrel a the chuck end..

 

We must remember here - that a reading of 0.14 actually amounts to a turned difference of twice that... and herein lay the greater portion of the 0.5 mm out that my drill bit was not centred when boring out the axle hole in the wheel.... I am hoping that this being off centre has "deflected" and flexed the shaft of the drill bit.. producing the 0.5 mm out of round that the wheel became........... pic..

 

002-test-bar-chuck-end-mail.jpg

 

 

So - we now need to adjust the tailstock.. It is made in two parts... the base, which fits securely located onto the corresponding V of the lathe bed.

It is soundly positioned by the "V" groove in its base... the other side has a large flat base which runs along the other side of the lathe bed....

The top half of the tailstock has the Morse #2 tapered spindle in it... the body which houses this is attached to the base by a screw, It can be adjusted laterally by loosening this screw and moving the top half either side...... to remove any clearance in the slide, a gib screw pushes one half firmly against the other half... pic

 

003-tailstock-gib-screw-mail.jpg

 

 

And deep inside the bottom half, we find the lock screw - holding the two halves together... we will shortly come back to this area.... for now, there does not appear to be anything amiss.

 

004-tailstock-slide-lock-screw-mail.jpg

 

 

Ok - having explained how the two halves work... here is a pic of them separated... you can see the "working surfaces" of the tailstock slide. The top half simply slides across in the bottom half... the gib screw is turned in to take up any slack, and the adjustment is checked again. When set, the lock screw then securely holds the two in exactly the set position... so far, nothing out of the ordinary - no chips in the metal or any signs of serious wear...

 

005-tailstock-slide-surfaces-mail.jpg

 

 

So, we take the base of the tailstock and fit it to the lathe bed.. to check for any clearance when mounted on the lathe bed... you can see how the base is securely held in position here...

 

006-tailstock-mount-surface-on-bed-mail.jpg

 

 

Not having found any issue... I then scoured the surfaces of the tailstock base for wear or marks.... the machining isn't great - but it shows that it is bedding in with use... however, there is more wear on one side of the "V".. and this may have accounted for the adjustment going positive (negative at the chuck end)...

I need not do anything here - there is no rocking on the lathe bed... this is simply a case of the poor machining of this tailstock base bedding in........ which will get better with use.... further, we must understand that this is not a "working" surface.. the only time this base gets any wear, is when I unlock the tailstock and slide it along the lathe bed.... bearing (excuse pun) in mind that I keep my lathe well oiled.... and clean. It is cleaned many, many times during a session to remove any swarf or chips from wearing the moving surfaces.....

 

Pic

 

007-tailstock-V-slide-mail.jpg

 

 

We're getting nearly three hours into the strip down now.. and I have really not found anything other than a little bit of bedding in wear.. but, I did find it and decided to put the lathe back together and run dial indicator over the test bar again.

 

I set up the two halves at a reference line I scribed into one of them.... and "bumped' the two into a new alignment.. using (as Munter puts it) my "eyechronometer"..

I believed I had this incorrect 0.14 pretty close.. and re-assembled the lathe.. fitted up the test rod and again ran the dial indicator.... "0.14" negative again..at the chuck end.... grrrrrrr.

 

I repeated this five times... and each time, it returned the same 0.14 negative... grrrrrrr I had to take a much closer look at "why"...

 

On the bench, I made absolutely certain that the two halves slid smoothly... and that the gib screw was not moving.. I checked the inside of the slide way for marks that the gib screw may have been "re-locating" when nipped up... nothing...

 

I then decided to removed the lock screw.... and found this!... pic

 

008-tailstock-lock-screw-base-mail.jpg

 

If you look closely at the slotted hole.. you'll notice a detent... where the washer under the lock screw had forced an impression into the metal of the slotted hole..

When the screw was tightened up, the now domed washer - was pulling the lock screw back into a set position.. that being where the detent has developed.....

 

I rummaged through my washers boxes and found three thick flat washers...slid them onto the lock screw - then fitted the screw into the hole.... lightly nipped up the screw by finger and found that I could now locate the two halves exactly where I wanted them....

 

However (yes, there's more)..... I have found a defect in the design of the lathe....

The purpose of this screw is not only to adjust the tailstock into true alignment with the chuck centre... but also to afford "laying" over the tailstock... so that a "tapered" shaft can be turned...

 

I found that the "cam lock" (lever/cam arrangement which locks the tailstock onto the lathe bed) fouled the tailstock adjustment in anything but perhaps 2 mm either side of centre........ I would have found this if I'd wanted to turn a tapered shaft.....

I will need to pull this apart and fit it to the Mill... and create a slot for the cam lock shaft to clear as the top is moved across the base.... another project coming up...

 

So, we now reset out tailstock head on its base and tighten up the gib and lock screws... re-fit it to the lathe and run the test rod.... I did this six times in all.. with very tiny "nudges" each time to remove the negative from the chuck end.... I got there, and am very happy tonight.. it has taken me all day to find, rectify and adjust the tailstock... I hope that anyone else with one of these otherwise great little lathes has learned of my issue.. and will be able to identify it if it arises in theirs...

 

finally - three successive pix of my final results.... the test bar and dial indicator revealing the following readings at - chuck end, centre and tailstock end.... I'll sleep better tonight....

 

009-test-bar-chuck-end-mail.jpg

 

 

011-test-bar-centre-mail.jpg

 

 

0010-test-bar-tailstock-end-mail.jpg

 

 

 

So folk - a whole day to correct this......and, apart from a tiny bit of wear on the V block of the tail-stock.... all down to one flimsy little washer that should have had a much thicker and stronger one fitted at the factory.......

 

And now - tomorrow brings us back to attempting to turn #7 wheel - hopefully, it will run true on the axle....

 

frats,

Rosco

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C3 huh..... :blink: Still Siegs are the ones to get.

 

Sutton drills are very good, never been able to order Sutton drills from the local bearing supplies here, not in the sizes I was chasing anyway. A minimum quantity order thing I recall. Can get the the #42 (.0935) drill at local bearing supplies readily in other brands though.

The .0925 drills I have are Kyocera, off Ebay I know Sutton do a 2.35mm drill, same as .0925 or close enough. # 42 is the one to get unless you have a heap of NSR axles.

 

I use the same small hand feeding chuck that you have to drill axle holes but put it in a MT2 ER25 chuck in the tailstock, its not protruding as far as when put the drill chuck. Purchased all these from Arc Euro trade many moons ago. Way before Ausee Machines and tools was around. They have the same products. This is generally how I do axle holes and is sometimes good, sometimes just ok as far as concentricity goes

Sometimes a fair amount work goes into finishing detail or getting a particular feature like a disc brake look or wheels with multiple components and forget to do the hole for the axle prior. This is when I resort to the 2.3mm drill finished with the miniature boring bit as I feel like I have more control on the final outcome being more concentric. Drilling it is a very touchy feely thing and you dont know if the wheel is good or buggered until its drilled.

 

Re checking tailstock alignment; Be sure to measure along the shafting when the tailstock is wound in AND again when it is wound out. A variation here will show that the tailstock quill is not on a concentric path.

 

I took a photo of the drill bit borer and a simple axle reamer I use to follow this method up with, but my computer cautions when Dropshots tries to load

Who's the go with Photo hosting these days? Its been a while since I've done it.

 

cheers

Edited by slo1quick

"Me Auntie's a Jack !!!"

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Great investigative work there Rosco's, you have demonstrated great tenacity in delving into the cause of your problem.

A day spent digging, but not wasted.

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Thanks Slo.... I have the ER 25 collett holder, will give it a go.

Thanks for the tip on purchasing a #42 drill bit... I have some bearing suppliers nearby, will give them a call....

 

As for posting images... I was put onto Photoimages... here's the link..

 

https://postimages.org/

 

free and so far, has worked a treat for me.. takes a bit of getting your head around if posting multiples... I just go with one at a time.. and do a copy/paste into my thread using the second bottom line url thingy....

 

Yes, look forward to seeing your boring bit... might have to have a go at making one myself.

 

I will centre drill the next wheel prior to drilling it... after boring out the recess.

 

I have a dividing head and rotating table for the mill.... the possibilities of using this for wheel detail is endless... if I do have a go at using it, I will drill holes in the wall of the rim to give a "vented" look... need to make a central hub on both sides of the wheel to do this though... maybe a long time off yet, but I'd love to have a go at it...

 

Thanks again, Slo... will let you know how I go with the #42... and checking the quill of the tailstock over it's length... easily done with the test bar... just slide the tailstock back on the bed and extend the quill.... and take another reading.... I tightened up the gub screw of the quill - that was loose too... may not make any difference to accuracy - but it has taken up some travel slack...

 

frats,

Rosco

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Hope so, Shaymus.... tomorrow will reveal if I have wasted a day... no matter, I'm retired - all the time in the world (NOT!).... blasted washer - what were they thinking?

 

frats,

Rosco

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Slo1quick - I use postimage on the PC (postimage.org from memory?)

Power is out here (storms) so can't check at the moment!

 

Oops, been a while between reading and posting - Rosco's beat me to it!

Edited by Shaynus

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Just did some calcs for the #42 Slo - by golly, that's tight.... 2.38 mm axle...... .0935" = 2.36728 mm..... .0925" = 2.3495 mm.....

I'm keen to get these now...

 

Yes, Shaymus.. I believe I dips me lid to you for putting me onto Photoimages...

 

frats,

Rosco

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Thanks for the link guys!

 

Yes Rosco, working to very tight tolerances. It really makes you appreciate how much time and effort the wheel manufacturers put into their wheels!

 

 

 

Broken drill with basically one flute ground off. This gives you an idea of the leading angle, which doesn''t really matter, its just what it ended up as. The tip is rounded with a 1200 grit diamond stone to take sharp point off. Got no idea what radius just a few haphazard strokes. I dont trust plunge boring it into the face of the stock but ok to just take a whisker of material off. I use a loupe when eye balling this into position. The straight nail looking thing to the right is the simple reamer to follow up the bore. It is a bit of 3/32 W1 silver steel sanded in a drill to be a near perfect fit for the slot it axles. One end is a tri point and the other just at an cute angle, the surfaces are polished with Arkansas stone to sharpen them up. Its a simple reamer to make and one that can be made using the axle the same as what is intended for the rim. This is really where the slightly undersized .0925 drill comes in handy too.

 

Hope this helps

 

 

Iphone-7-5-20-002.jpg


"Me Auntie's a Jack !!!"

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Ah-ha - got it... understand the reamer now, and how you have made the boring bit... I don't yet know what an Akansas stone is, but I'll look it up.

Love your work, Slo.... I can see years and years of experience in these tools....

I will attempt the reamer first.. you have jogged my memory in something I saw in one of my books - the L.H.Sparey one (The amateur's lathe).. almost my bible... self taught me how to set up my lathe and learn to operate it...

 

See if I can find a 4 mm HSS bit... grind off one flute and do a test run.. it is indeed fine scale for intricate parts... love the holder too.. square brass rod, I expect?

 

Thanks again, Slo - I'm off to bed.... my head is still running congrous with the chuck of the lathe.... spinning...

 

frats,

Rosco

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A bit of bad luck with wheel #5 but pretty sure you'll get it sussed pronto eh Ross.


bram1_zpsfkhrhndv.jpg

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#6 wasn't looking too good either, before I decided to stop work Bram... before I decided to check the lathe... we'll see today what fruit of my labours results in...

 

frats,

Rosco

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I use easily available slot car axles as a reamer, like SLO ‘s simple reamer.

These cheap lathes do need a lot of work to get good results.

I have no idea of the hours I put into mine to get acceptable results.

As for making wheels, I simply cannot spend the time, used to make some when I have access to top line tool makers lathe,even then it was hard to justify the time it took for a pair of wheels.


Phil

 

Hobart Miniature Car Club

 

Tassie Resins

 

Email

 

 

 

 

 

 

Logos%2016_17.small_zpswkcwjf0q.jpg

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Yes, Phil - concur..... I have put a huge amount of work into this lathe since getting it. Quite a few recommended modifications - all of which have made it much smoother running and accurate... still a way to go yet, it seems.... read on...

 

Wheels - I am actually enjoying making these wheels, as frustrating as it is... I will get there, but I'm not where I want to be just yet.

I don't expect I'll get the accuracy of Slot-It wheels - by golly, they are simply delectable... but, if I can get them running as true - I will have achieved my aims.

I am turning quite well now... not one "rinse" (my term for mistake..... emanating from when dentist makes a mistake with the drill... "rinse") in all the time I have spent on the machine in the now 8 wheels....

 

Working on the next report - lots to tell.

 

frats,

Rosco

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Ok folk,

Today.... all day - 1 wheel..... #8. it's a darned good thing I purchased 1.6 m of this 17 mm ali rod.... I might just get 4 wheels out of the entire length of it.. it seems...

 

I set out this morning with full commitment to "just" turning one wheel.... didn't care how long it took, but I wanted this one right.

I have been getting better and better at turning the wheel itself.. in fact, I'm getting within 0.01 mm for step diameter and width plus rim diameter and width.

Recess is still varying by less than 0.025 mm here and there... but I'm happy with it. I simply can't get my calipers into the wheel to measure it accurately... by the time I part the wheel of, it can vary by the above amount.. My aim is 3.0 mm from the outer rim edge... to accommodate Munter's insert... all of them thus have have more than done that with only the very small difference in depth of the insert... which can be "manually" fudged when it comes time to glue them in...

 

Ok - here is today's edition...

 

I turned down the wheel almost perfectly... (pats self on back.. again). Please excuse failing to wipe off the black texta marks on the wheel. (I find using texta on the ali allows me to easily mark and check settings of the cutting tools when setting up the next cut).

 

And then, we came to drilling the axle hole...

I spent ages on setting this up and checking it before making the first cut...

 

In the pic below, you can see a 1.0 mm centering drill positioned ready to "strike"... I ran this in and out from the wheel many times before attempting to start.

I could not fault yesterday's work in aligning the tail-stock up... this centering drill was absolutely spot on dead centre of the rim... the point of it marked exactly where the centre dot of the wheel was from turning it... I simply couldn't make a better start.... or I wouldn't have.... pic...

 

01-8-centred-mail.jpg

 

 

As you can see in this pic, the 1.0 centering drill has marked the exact centre of the wheel... so far, so good...

 

 

02-8-centred-1-0-mm-mail.jpg

 

 

We have run the pilot of the 1.0 mm centering drill in.. and withdrawn... it is exactly where it should be.

 

I then swap to the 1.5 mm centering bit and run the pilot into the wheel again.. withdraw - and perfect.... I have "high hopes" this time... read on...

 

03-8-centred-1-5-mm-mail.jpg

 

 

Being satisfied with the pilot of the larger centering bit, I decide to run it further in sufficiently enough for the following 1.0 mm drill bit to centre and commence to bore out the hole.... I did not want to go into the wheel any further than can be seen in the pic... the cut shown is pretty much the width that the 2.38 axle hole will be....

 

04-8-centred-1-5-mm-mail.jpg

 

 

All good so far - we have lunch then I'm back into it again..

I fit up a 1.0 mm Sutton drill bit.. check that is exactly centre in the tail-stock mounted drill chuck and run it in carefully by hand to check that it sits perfectly centre in the pre-drilled centre... it does.... I can't fault my actions and firmly believe "this" will be "the" wheel...

 

I set the lathe speed to 100 rpm and very slowly start to feed in the drill bit... fraction by fraction, withdrawing and clearing away the swarf from both drill bit and hole..

We continue this for a good 5 minutes.. bit by bit... absolutely no indication of the drill bit beginning to wander...

 

In and out, in and out as each micro cut is made...

 

We get to about 2/3rds of the way into the wheel and "presto!".. the drill bit chucks a wobbly.... I stop, shriek and turn hit the emergency stop button... grrrrrrrrrrr

 

Then I see it - "Eureka!"....

 

I believe I may have found what has been causing these axle bores to go off centre... the pre-drilled grub screw hole...

I measure the distance into the wheel that the drill has gone - and it is exactly at the opening of the pre-drilled grub hole....

 

So - I'm sort of grumpy, but also relieved.. I have found "something" else.... first the tail-stock out of whack.. and now this blasted grub screw hole...

 

I am hoping one of my mentors can assist with this ... ?

Is it usual practice to pre-drill the grub screw hole prior to boring out the axle hole.. or, is this grub hole drilled post axle boring..?

 

If this is the case, I had pre-drilled all 11 grub holes in this piece of stock....

 

A "lightbulb" moment occurred later this evening and I decided to fit the stock with the remaining 4 grub holes already drilled back into the Mill.. and have drilled them right through..... there should not now be any deflection as the drill bit reaches the grub hole...

 

I managed to "coerce" the 2.38 mm drill bit through wheel #8... and it runs much truer than #6... and pretty much as well as no's 1-4... but, I should not have to hand work the axle hole... it should drill through with the two suggested cuts after using a centering drill.....

 

thoughts, anyone....?

 

And - another lightbulb moment since... I will centre a piece of unturned stock in the lathe tomorrow - and drill as per today - if it deflects, we are looking for something else than the tapped grub screw hole.... grrrrrrr learning curve "shooting the moon" - again....

 

frats,

Rosco

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If you could buy the perfect wheel for every occasion, would you bother buying a lathe? ....Myself, I would still buy the lathe :rolleyes:

 

I have learnt not to drill a hole in stock, even aluminium, with an opening perpendicular to the hole Im drilling with a drill bit any smaller than that of the perpendicular hole, bore yes drill no. Even with larger drills though they are more forgiving.

 

I always leave the grub hole till last, because I drill it... this rim design wont allow for drilling last, end milling doable, but not drilling. The pilot hole for your grub screw was necessary because it was located on the edge of the rim where there is an uneven load on the drill. The drill has a tapered tip which will follow the path of least resistance readily. Same as the grub screw hole which penetrates into the proposed axle hole, it has created a path of least resistance. Mill bits have a square end which has the ability to hold true even under uneven load, within specs.

 

Keep up your diligence Rosco, though its strayed from the build a little it has highlighted an integral build problem associated with the build. There are many off the shelf items available for putting a slot car together but sometimes its just enjoyable to be able to make something at will and with a little bespokeness about it.


"Me Auntie's a Jack !!!"

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Thanks Slo - I was hoping you'd chime in on this before I go and have another attempt tomorrow..

Yes, understand your practice of not using a drill smaller than any hole which runs into the proposed bore.... I have given this further thought.

The issue concerning drilling the grub post turning can be by-passed.. and I have come up with an alternative procedure...

 

I can drill the grub hole only as far as the top of the hub (6.35 mm) or maybe a tiny bit more...pre-lathe.

 

By doing this - the grub hole can simply be drilled post lathe in the mill..... the recess for the drill bit in the wall of the rim will be already made (1/2 hole sided) and I will not have a hole in the lateral centre line of the wheel to deflect the boring of the axle hole...

 

This is my latest... plan "E"... A through D have proved unsatisfactory... bit of a pain, but if I can get the axle bored true - I will be very happy.... the grub need not be anywhere near as critical... as long as it is centred on the axle....

 

If you look at a Slot-It wheel, they have overdrilled the wall of the rim... it is not threaded. I believe this is their machining process.

 

But, they have CNC machines - we can't compete with those...

 

Your thoughts?

 

frats,

Rosco

Edited by rosco01

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Been thinking along these lines:

Q: Why did you bother doing that?

A: Because it was quicker...X

Because it was easier...X

Because it was cheaper...X

 

Because I wanted to... tick

To prove I could do it...tick

To have that sense of achievement...tick

Because I wanted to...tick

To make something unique...tick

Because I could...tick

 

Ticks the right boxes in my mind!

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Not drilling the grub all the way through will remove the path of least resistance. You need to drill down as far as and slightly into the boss of the rim to make a starting point to continue drilling your pilot for the grub. Though, As you've demonstrated, when you continued the grub screw hole through with the drill, you equaled up the path of least resistance and the the hole was ok, yeah?


"Me Auntie's a Jack !!!"

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