A little Machinist advice please

[AndyM]

Sorry, I meant the other way around, to account for the off-set. I estimated it at 26.8mm here:

View attachment 156199

OK - did several takes - looks like 28.6 is the answer.


The difference (26.8 vs 28.6) looks to be in the 12 height - I measure 14.5. That little rise at the base is an additional 2.2 mm. +/-

 

[PoTreeBoy]

I would be interested in seeing the 10mm bore bushing - is a link possible?
A cast iron alternative to the JD version for a similar price is interesting option. Even better if a cheaper cast pulley that matches' the bore can be had.

Taper lock bushings clamp on to the shaft and are good for oscillating loads. If you decide to go that way, double check the pulley diameter. The one TOH listed might be too large, but they're available in various sizes.

 

[TheOldHokie]

I would be interested in seeing the 10mm bore bushing - is a link possible?
A cast iron alternative to the JD version for a similar price is interesting option. Even better if a cheaper cast pully that matches' the bore can be had.

Here it is.

Taper bush 1210 bore 10mm PN: 62250310 – Maedler North America

maedlernorthamerica.com

Use it with any taper lock sheave with a 1210 center.

Dan

 

[TheOldHokie]

Taper lock bushings clamp on to the shaft and are good for oscillating loads. If you decide to go that way, double check the pulley diameter. The one TOH listed might be too large, but they're available in various sizes.

Here is a QD bushing. Use it with any QD sheave that has a H bore.

https://a.co/d/f9NdOmF

Dan

 

[lynnmor]

The 10mm bushings mentioned above still need a 1/8" keyway, you will need a 10mm bushing for a 1/8" broach to do it.

 

[TheOldHokie]

The 10mm bushings mentioned above still need a 1/8" keyway, you will need a 10mm bushing for a 1/8" broach to do it.

I have my doubts about the key actually being 1/8". Even if it is a file will make it a 10mm x 1/8" step key PDQ.

Dan

 

[torch]

The 10mm bushings mentioned above still need a 1/8" keyway, you will need a 10mm bushing for a 1/8" broach to do it.

Not a problem actually -- the 1/8" broach is an A width as is the 3mm broach. I tried it and the 1/8" fit perfectly in the 10mm bushing. The only trick was the shimming for the second pass, but I found a shim combination that will only be a few hundredths (of a mm) deeper than standard. That much tolerance shouldn't be an issue.

 

[TheOldHokie]

Not a problem actually -- the 1/8" broach is an A width as is the 3mm broach. I tried it and the 1/8" fit perfectly in the 10mm bushing. The only trick was the shimming for the second pass, but I found a shim combination that will only be a few hundredths (of a mm) deeper than standard. That much tolerance shouldn't be an issue.

You dont need to rekey the bushing. File .003 off each side of the 1/8" key. Ten minutes work and zero cost.

Dan

 

[torch]

Ok, so I think I have all the numbers now. If I was to machine a new pulley from billet, it would probably look like this (although I'd 3D print a sample first to verify it on the machine):

I'm not sure what you have for local machine shops around there, but one could take that drawing and make up a pulley. Wouldn't be cheap due to labour. Mind you, if they have a CNC lathe, I could send you the .step or .stl file.

Might be something a local high school shop might tackle for you though. If there's enough school year left.

Hmmm. Actually, I wonder what kind of load is on this belt? I wonder how a 3D printed version done in carbon-fiber reinforced nylon would hold up? I've done gears and cogged belt pulleys that way quite successfully, but I've never tried a V-belt.

(For those doubters in the crowd, I am a mentor with Hoya Robotics, team 4152. Many if not most of our timing belts were driven with such pulleys this year. Not one mechanical failure all year, from regional competitions through the World Championships. A short video showing it in action is here:

) .

 

[TheOldHokie]

Ok, so I think I have all the numbers now. If I was to machine a new pulley from billet, it would probably look like this (although I'd 3D print a sample first to verify it on the machine):

View attachment 156223

I'm not sure what you have for local machine shops around there, but one could take that drawing and make up a pulley. Wouldn't be cheap due to labour. Mind you, if they have a CNC lathe, I could send you the .step or .stl file.

Might be something a local high school shop might tackle for you though. If there's enough school year left.

Hmmm. Actually, I wonder what kind of load is on this belt? I wonder how a 3D printed version done in carbon-fiber reinforced nylon would hold up? I've done gears and cogged belt pulleys that way quite successfully, but I've never tried a V-belt.

(For those doubters in the crowd, I am a mentor with Hoya Robotics, team 4152. Many if not most of our timing belts were driven with such pulleys this year. Not one mechanical failure all year, from regional competitions through the World Championships. A short video showing it in action is here:

) .

Off the shelf cast iron replacement for $55 delivered to my address.

HX10MM Bushing | 10MM "H" Pulley / Sheave Bushing for Leeson Power Drive Sheaves

HX10MM Made in China QTL Quick Detachable Taper Bushings Includes Screws GGG40 Ductile Metal Cast Iron Bushing for Pulley or SheavePicture is illustration only-actual item may vary.

electricmotorwarehouse.com

AK39H Pulley | 3.75" OD Single Groove "H" Pulley (bushing not included)

AK39H Made in ChinaSingle Groove Cast Iron PulleyUse with A or 3L-4L BeltsRequires "H" Style Bushing; Uses QTL Quick Detachable Taper BushingsContact Electric Motor Warehouse for assistance to select correct bushingCast Pulley SheavePicture is general representation of pulley. It may vary-but...

electricmotorwarehouse.com

 

[torch]

Off the shelf cast iron replacement for $55 delivered to my address.

Nice. He might need a spacer to ensure it is correctly aligned with the drive pulley, but that could work. The pulley does say it is compatible with 3L belts as well as 4L and A series, so while the OD is 3-3/4", the pitch circle of a 3/8" belt is probably pretty similar to the OEM since the 3/8" belt will ride lower in the V.

I wonder what size the keyway is? They don't give any actual dimensions other than the bore.

 

[TheOldHokie]

Nice. He might need a spacer to ensure it is correctly aligned with the drive pulley, but that could work. The pulley does say it is compatible with 3L belts as well as 4L and A series, so while the OD is 3-3/4", the pitch circle of a 3/8" belt is probably pretty similar to the OEM since the 3/8" belt will ride lower in the V.

I wonder what size the keyway is? They don't give any actual dimensions other than the bore.

I am sure the keyway is the standard 3mm.

Dan