17 replies to this topic

[Yngwie]

I have been looking around and have seen that people have been re-taping the holes in their wheels and gears to accept larger grub screws. What type of tool is required to do this? I am thinking of re-taping a few wheels which no longer accept the M2 screws.

Is there any trick to this?

Kind Regards

John

[kalbfellp]

You need to buy the correct size tap,tap handle and drill along with some new grub screws. These are the common sizes used in slot car wheels.

1-72 UNF (1.854mm)
2-56 UNC (2.184mm
3-48 UNC (2.515mm)
4-40 UNC (2.845mm)
M2x0.40 (2mm)
M2.5x0.45 (2.5mm)

[Yngwie]

Thanks. Where do I buy these things Phil?

[Mohawkk]

any half decent tool shop (re. NOT hardware) should have them...
only thing is to get them in that small of a size.
Not sure if you can get just the tap, or you need to buy the tap +die set.

[Yngwie]

Thanks Phil and Kai. Just had a look here. Tap Wrench

Is something like this all I need? (3rd one down - Suits taps 2.5 - 5.00 for M2.5)

[slotbaker]

Yep, that one would suit.

You can just buy the tap, and don't need tap and die set. The die is for threading external threads.

Taps come in 3 grinds for engineering. Taper, Intermediate, and Plug.
I would suggest just getting the Intermediate.

They are also usually available as a "Gun" tap used in tapping machines. You could also get the Gun tap, as it can be used by hand.

Unless you're going to do a lot of tapping, you don't need the tap wrench either. You can just a small shifter, although the wrench does make it easier.

The only other thing you may consider, are drills to suit the thread.

You can find this on Google buy looking for 'drill tapping chart' or similar.
Here are a couple, Here and here.

You should be able to get the drills from the same place as the taps.

Chances are that you may not need the drills, as you would be tapping out very little material, the tap should be OK.

[kalbfellp]

If you have not done much tapping don't try and use a shifter! The taps are too small and you will either break the tap or oval the hole.
Many engineering suppliers do not carry such small taps. Look at model engineering/train suppliers.
This guy is a good source of screws.

Kens suppies.

I could not find anyone with all the taps recently so ordered from the US.

[munter]

Visit My Website
This tap is what I have used, supplied from this website.
Gill is a top guy and you should have no worries in dealing with him.....
....he just won the Aussie 1/24 open title too.
regards

ps I use a small T handle which I have had for years.
It helps keep the tap in position/vertical as I am turning the tap ino the hole.

[munter]

Quote

Is there any trick to this?

No tricks but some tips

1) hold the rim firmly ...maybe in a softjaw vice
2) turn the tap forward 1/2 a turn and back 1/4 turn....I sometimes crank it in a couple of turns at the start before I do this backing off.
This 1/4 turn back clears the crap you have cut out of the thread.
3) some fluid can help...kero or light oil,crc maybe
4) keep it slow but straight

There are bound to be more so anyone feel free to add to this.
regards

[kalbfellp]

The 4:40 tap may be a too big for some wheels! I used to retap all my Slot it gears and wheels but found that some do not have enough room for the 4:40 grub screw.

[Vinno]

John have a chat to Joe on the weekend, he is a fitter by trade and can advise you.

[schuey19]

Vinno, on Apr 5 2010, 06:11 PM, said:

John have a chat to Joe on the weekend, he is a fitter by trade and can advise you.

I was about to say the same!

[Yngwie]

Thanks guys. Of course, how could I forget the Slot Doctor!

Regards

John

[SuperSlab]

OK, this is going to sound silly, but....

Running a tap into something as small as a wheel is tricky: very easy to get it crooked. I found it made it easier to turn the wheel on the tap, rather than turn the tap in the wheel. If that makes sense... I found that you can "feel" the wheel centering on the tap much better that way & I was less inclined to move/misalign the tap. Remember to twist the wheel backwards & forwards as per Munter's suggestion.

On the other hand, it might be that the only reason why I did it this way is that I come from the Southern hemisphere and I now live in the Northern hemisphere, so I tend to do everything bass ackwards.

[brockfan]

Tony, I do mine in the drill press.
I put the rim in a smooth faced vice and drop an undersized drill bit into the existing tapped hole just so can make sure the hole is vertical and square.
I drill the hole to the right tapping size if necessary then I put the tap into the chuck, remove the drive belt and just rotate the chuck by hand as I gently feed the tap into the hole....reversing as necessary to clear the swarth.
The hole comes out "dead nuts".....

[munter]

brockfan, on Apr 9 2010, 02:12 AM, said:

Tony, I do mine in the drill press.
I put the rim in a smooth faced vice and drop an undersized drill bit into the existing tapped hole just so can make sure the hole is vertical and square.
I drill the hole to the right tapping size if necessary then I put the tap into the chuck, remove the drive belt and just rotate the chuck by hand as I gently feed the tap into the hole....reversing as necessary to clear the swarth.
The hole comes out "dead nuts".....

sounds nice and precise.........just what you want .
regards

[FLY in the wall]

M2.5 should be OK unless the holes are out of round. This is because the size of a clearance drill for M2 is the same as a tapping drill for M2.5. The drill size is 2.05mm but a simple 2 will be OK.

You only need one tap, a plug tap. Which is the middle one if you see three in a picture.

Technique do what Munter says.

For wheels despite what one may think if the holes is not completely perpendicular it won't matter that much so do not worry too much about perfection. If buying a tap wrench get a T handle as they are better for small taps but you can always unscrew the chuck from your DIY hand drill and use it. It is a bit bulky but free if you already have one. I had to make my own. a simple bar one.

If you can't find any grub screw locally, www.modelfixings.co.uk will have them.

If you have never done anything like this before maybe look at this

I always knew that apprenticeship would come in handy for something.

Edited by FLY in the wall, 09 April 2010 - 08:36 PM.

[Rob]

Starting, intermediate and plug tap from left to right.
I only ever use a plug tap if im trying to get max depth in a blind hole.