Miniature Taper Lock fittings?

[Nate]

The Fischer Technik construction toy uses a flimsy version of this kind of fitting where there are tapered threads on the bushing and the pulley.

Do not ask me WHY the mfr of my machine chose 9.5 mm - I don't know!

Is it possible that it's a 3/8 inch part (about 9.53 mm) and the 8mm shafts are 5/16 inch (about 7.94 mm)?

You may be able to find parts for a 3/8 inch shaft regardless.

[Roger]

Is it possible that it's a 3/8 inch part (about 9.53 mm) and the 8mm shafts are 5/16 inch (about 7.94 mm)?

What a horrible thought!
It was built by an Australian company, and Australia went metric in the 60s, but it may be that the company was still using imperial in some places where they were dependent on American parts - such as ball screws and toothed belts.

Hum ... It's possible. I will have to find out when I take the XL pulleys off and put the GT2 ones on. Fortunately, since I am using split taperlock fittings, there is some room for a few 10s of microns variation.

Thanks for the suggestion anyhow.
Cheers
Roger

[Nate]

Is it possible that it's a 3/8 inch part (about 9.53 mm) and the 8mm shafts are 5/16 inch (about 7.94 mm)?

What a horrible thought!
It was built by an Australian company, and Australia went metric in the 60s, but it may be that the company was still using imperial in some places where they were dependent on American parts - such as ball screws and toothed belts.
...

FWIW It looks like Ringfeder does make a 7090 taper lock in that size.  (No clue why it's just that model.)

[Roger]

It looks like Ringfeder does make a 7090 taper lock in that size.

Indeed. I have enquired about pricing. I await the reply with great interest (and doubt).

Cheers
Roger

[Roger]

Photo as promised below. From top downwards:

Two large pulley blanks, one in PE and one in 6061. I KNOW the PE is not as strong as the 6061, but the diameter is 3x that of the smaller 6061 pulley, and I know the teeth on that size are strong enough. I know that nylon, in quite thin sections, is often used for toothed belt pulleys. So - an experiment. I suspect the teeth on the PE pulley will turn out excellent.
The PE blank has a taperlock unit in it, with brass nut. The big Q is whether the taperlock will hold against the PE, or whether it might slip. I don't know yet. I don't think cracking is a worry with industrial PE this thick. If it does slip I can put an Al bush insert into the PE with flange screws: commercial nylon pulleys have Al bushes and the nylon is molded around the bush.

Test GT2 pulley, 30T. Just one of a number of GT2 pulleys I have made. The others are actually in use. My cutter (which I made) may deviate from the official GT2 profile by a micron or two, but should I worry about a few microns when the belt face is fabric?

2011 Al alloy pulley in middle. There will be a 3:1 ratio between the big and small pulleys when they are finished. Yes, the bore in these blanks is tapered already: 3 degrees half angle.

TL insert on mandrel. It has 8.00 and 9.50 mm ends.
Taperlock inserts for 8.0 and 9.5 mm shafts: you can see the slightly different wall thicknesses.
TL inserts showing anti-rotation key slots used only when tightening the fitting
Pulley showing pin going through plulley into TL insert. (In this unit the key slot overlays the split, which has been hacked around a bit during experiments.)

Still to do: turn the ODs of the blanks down to correct values; cut GT2 teeth onto blanks; make up side flanges and fit to pulleys; fit and test.

Cheers
Roger

[mrehmus]

Not wanting to blow my own horn but I published an article on how to make taper lock bushings in issue # 11 of Model Engine Builder magazine. This type of mount for flywheels is frequently used (and made) by Model Engineers.

Tapers are always a bit tricky to cut because not only do the tapers, male and female, have to match, they must be cut directly on center or they will not have straight sides.

If you can find suitable locks, great. If not, contact me off the forum.


Mike

[Roger]

Not wanting to blow my own horn but I published an article on how to make taper lock bushings in issue # 11 of Model Engine Builder magazine. This type of mount for flywheels is frequently used (and made) by Model Engineers.

So many magazines, so little time. Thank you.

Tapers are always a bit tricky to cut because not only do the tapers, male and female, have to match, they must be cut directly on center or they will not have straight sides.[/quote
And trying to match the tapers on a manual lathe is a right pain. But with a CNC it is easy enough.
'On centre' - yes, a hidden trap. But it can be handled.

I have PM'ed you.

Cheers
Roger

[mrehmus]

I sent you the issue via SendThisFile.com. Let me know when you receive it please.

This approximately 10 HP supercharged V-8 model uses a taper lock on the flywheel if I remember correctly. THe engine is about 1 foot long, front to back.

[Roger]

Zip file received. Interesting article (and issue), for which my thanks.

Ah, model engine enthusiasts, and the smell of nitro ... (or ether+olive oil)

However, about half the article has to be devoted to explaining how to get +4.0 degree and -4.0 degree tapers on a manual lathe, with the admission that the 4 degrees will still only be approximate. This is fine if one is restricted to a manual lathe, but I suspect that most readers here will be running CNC machines. With a decent CNC lathe you just specify 4.00 degrees in the code and that is it. An extremely accurate match results. (Yes, I do have a manual lathe and a manual mill as well.)

I did have some reservations about scale. Your taperlock design uses 4 - 6 bolts to tighten the taperlock into the pulley. Some of the taperlock fittings I am making, or rather the pulleys they are being fitted to, would require 1 mm bolts for that to fit into the space provided. A shade too small I think. Instead I went for a single nut over the whole taperlock. That is just a detail: on a larger taperlock the flange+bolts would be better.

Cheers and thanks
Roger

[mrehmus]

Understand the CNC focus but Model Engineers, for the most part (us old guys) primarily use manual machines hence the care to explain how to do it right without a computer. The newer members of the community do use CNC as do I in a limited way.

A single nut is a good idea. I think I'll mention it to our clock-makers. The locomotive guys still use keyways.

The V-8 runs Sonoco Racing Fuel at 110 octane. Mainly because the automotive pump gas we buy in California goes off in about 30 days and racing gas does not. Aviation gas is also popular for the same reason.

[Roger]

I tried putting a keyway into the taperlock, but that meant drilling or broaching a 1 - 1.5 mm hole down the boundary between taperlock and pulley at the taper angle for maybe 10 mm. That was ... difficult.

The single nut works very well imho.

Yeah, I understand about your more 'senior' members.  :) Given the hassles of maintaining a CNC, I don't blame them.

Cheers
Roger

[Roger]

In the end, I found that a 2011 aluminium taper inside a 2011 or 6061 aluminium pulley on a steel shaft did not need a key of any sort. Once the taper has been done up tightly, you need a hammer to break it loose. All very successful.

I will have to make a good gear-puller to get them back off the shafts ...

Cheers
Roger