Hobbing a Pulley for driving accessories for Model Steam Engines or Toy Steam En

[Jim Dobson]

Hobbing a Pulley for driving accessories for Model Steam Engines or Toy Steam Engines
This worked out really well for a first attempt, I've been wanting to try this for ages to stop belt slippage on pulleys and drive wheels when running accessories off steam engines under load which can very often be a problem as some engines lack the power to be able to put a lot of tension on a small round drive belt.
It’s a great hobby and pastime working on your metal lathe or metal milling machine making parts for model engines and model or toy steam engines.

[SwarfnStuff]

Thanks for posting this Jim.

I have seen this done for gears where folk search for of the correct pitch. I think that was for a worm gear with the worm being of a matching threaded spindle.

Less messy than the old belt grip fix especially for little model engines and as you say the thread / pitch is not really important just gaining grip without high tension.

Thanks again,
John B

[Jim Dobson]

Thanks John, really happy how this turned out because its always been a problem especially with smaller less powerful steam engines that you can't put a lot of tension on the drive belts with.

[efrench]

The angle on the V pulley looks too shallow.  V pulleys for round belts on the Misumi website show a much steeper angle. I've had good success using pulleys with  a 45 degree included angle. 

[Jim Dobson]

The angle on the V pulley looks too shallow.  V pulleys for round belts on the Misumi website show a much steeper angle. I've had good success using pulleys with  a 45 degree included angle.

We're talking about toy and model steam engines not industrial applications. I mention in the video that the drive pulley is out of my scrap box and being used as a test piece in the experiment an that I would be grinding a HSS cutting tool to a better profile.

[efrench]

I use a lot of round belts and pulleys on my Rose engine driving cutting frames.  The only time they slip is when the tension is too low.  It may be worth trying a steeper angle to see if that resolves the problem.

[Jim Dobson]

I use a lot of round belts and pulleys on my Rose engine driving cutting frames.  The only time they slip is when the tension is too low.  It may be worth trying a steeper angle to see if that resolves the problem.

Some of these toy engines that we use to run toy accessories are very (very) low powered oscillators and tension on the belt can be enough to stop them in their tracks. 

[Jim Dobson]

Here's some photos of a vertical transmission that I made some years ago that I have 'retrohobbed' one side of the drive pulleys on this morning.

 

 

 

[Jim Dobson]

Retro Hobbing.....(Worm Gearing) I've been busy hobbing my vertical and horizontal transmissions I made some years ago plus a few other accessories.

Things I've learned from doing many now - what works for me.



Lathe 400rpm

Use lots of WD40 and a toothbrush to keep clearing away the chips

Very critical is to have the tap centered perfectly in the middle (spend some time eyeballing this) if there's any chatter whatsoever the tap is either trying ride up or down

Don't put too much pressure on the tap, its not needed and just keep going in a couple of thou at a time. When you're at the depth you want, let the piece rotate at least another 4x for a really clean cut.

 

 

 

 

 

 

 

 

 

[Jim Dobson]