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

 

[AndyM]

Great crowd at this place- ask a simple question and get education, options galore and lots to think about.

Torch
I appreciate the effort you have made to draft up a model; trying to get a local machine shop involved is likely a pathway to the road of ruin. If your interested in making something up we should get a PM going.

The idea of a carbon fiber option is interesting if you want a guinea pig lets talk - what's the worst that could happen - I have to pick up a bunch of carbon fiber pieces. I will gamble a few bucks on that.

Dan
The pulley and bushing look great to me. If I was in the US it would be a no brainer IF the 3 3/4 would fit. I have a 4" that does not. The US$40 sound great but add FX, shipping and taxes gives me pause to gamble. I have also had some problems with US industrial suppliers willingness to ship to the Canada. Cross that bridge if/when we get there.

Thanks to all that chipped in.

 

[torch]

I appreciate the effort you have made to draft up a model; trying to get a local machine shop involved is likely a pathway to the road of ruin. If your interested in making something up we should get a PM going.

The idea of a carbon fiber option is interesting if you want a guinea pig lets talk - what's the worst that could happen - I have to pick up a bunch of carbon fiber pieces. I will gamble a few bucks on that.

Not sure when you need this by, but given it's for a lawn mower, I assume you want it before the winter. ;-)

I've been giving the 3D printing concept more thought. The problem with printing a V-belt is it would need to be printed horizontally, so the belt would be wedging the layer adhesion -- the weakest point of 3D printing even using CF reinforced nylon filament. We were making cogged pulleys and the forces are across the layer lines so this is apples to oranges. It might still be fun to try, but I would redesign things a bit, making the top of the pulley flat with a recess for the nut and washer to better distribute the delaminating force.

The pulley and bushing look great to me. If I was in the US it would be a no brainer IF the 3 3/4 would fit. I have a 4" that does not.

If I understand correctly, the problem with the 4" pulley was the belt tension rather than the physical diameter of the pulley hitting something?

Note that the pulley referenced by Dan is listed as compatible with both 3L (3/8" wide) and 4L (1/2" wide) belts. The angle of the V in both cases is the same, so the 3L belt will ride further down in the groove than a 4L belt (the point that the belt rides at is known as the "Pitch Diameter"). Pitch diameter can be measured using an appropriately sized round pin placed tangentially in the groove. The point where the pin wall contacts the groove walls marks the PD. For a 3L belt use a 0.375" pin; for a 4L belt the pin is 0.4375".

A bit of math shows the effective pitch diameter of a 3L belt in a 4L sheave is about 0.19" smaller than for a 4L belt in the same sheave. So I think the belt tension of the 3.75" OD pulley Dan suggested would be damn near the same as your current 3.5" pulley.

The US$40 sound great but add FX, shipping and taxes gives me pause to gamble. I have also had some problems with US industrial suppliers willingness to ship to the Canada. Cross that bridge if/when we get there.

There are Canadian suppliers of the same product. These guys are in the Toronto area and it sounds like they might even be manufacturing some of this stuff to order.

H style 10mm hub: https://www.motioncanada.ca/products/sku/02167588;origin=sayt

H style 3.75" OD pulley: https://www.motioncanada.ca/products/sku/02910163

Now these guys actually spec some dimensions and I see the H style hub is 1-1/4" (32mm) thick through the bore hole. I'm concerned that might be too tall for your application -- yours is thinner through the bore -- including the bit that has to fit inside the recess. Now you could shim it up with a spacer or even some washers to clear the casting recess, but will there still be sufficient thread left for the nut on top? Will a split bushing hub tend to wobble if a substantial part of the bore is around threads instead of being firmly supported?

I wonder if this G style hub would be better, as it is only 1" through the bore:

https://www.motioncanada.ca/products/sku/08537688;origin=sayt

I didn't go hunting down a pulley for that one, but it might be worth giving these guys a call to discuss the options.

 

[torch]

I should add that my concern over the hub thickness is related to where the pulley centerline ends up. The width of the pulley doesn't really matter, it's where the belt rides. It needs to be aligned with the drive pulley to avoid problems.

 

[torch]

Thicker wall version for 3D printing:

 

[torch]

I printed one off in cheap PLA as a proof of concept. The overhang of the upper half of the sheave is proving a bit challenging, so I've tweaked the supports a bit and am currently printing off a second prototype. But after a bit of post-print processing with a file, it actually seems like a viable idea. Here it is running at 500 rpm or so with a 3L belt:

[video deleted because there's no way to stop autoplaying the next video in Dailymotion. I won't use them again]

If you want to watch the short video clip you can download it from here instead.

(and yes, it's driving a hand-held bicycle training wheel )

 

[AndyM]

Not sure when you need this by, but given it's for a lawn mower, I assume you want it before the winter. ;-)

We are entering our dry season - won't be much grass to cut and the battery version can handle that. The JD is the answer when we get heavy wet grass (early spring, late fall). No panic.

I've been giving the 3D printing concept more thought. The problem with printing a V-belt is it would need to be printed horizontally, so the belt would be wedging the layer adhesion -- the weakest point of 3D printing even using CF reinforced nylon filament. We were making cogged pulleys and the forces are across the layer lines so this is apples to oranges. It might still be fun to try, but I would redesign things a bit, making the top of the pulley flat with a recess for the nut and washer to better distribute the delaminating force.



If I understand correctly, the problem with the 4" pulley was the belt tension rather than the physical diameter of the pulley hitting something?

There is a belt guide that measures 3 5/8 between the horns - the biggest pulley that will fit is 3 1/2 - I just checked.

Note that the pulley referenced by Dan is listed as compatible with both 3L (3/8" wide) and 4L (1/2" wide) belts. The angle of the V in both cases is the same, so the 3L belt will ride further down in the groove than a 4L belt (the point that the belt rides at is known as the "Pitch Diameter"). Pitch diameter can be measured using an appropriately sized round pin placed tangentially in the groove. The point where the pin wall contacts the groove walls marks the PD. For a 3L belt use a 0.375" pin; for a 4L belt the pin is 0.4375".

A bit of math shows the effective pitch diameter of a 3L belt in a 4L sheave is about 0.19" smaller than for a 4L belt in the same sheave. So I think the belt tension of the 3.75" OD pulley Dan suggested would be damn near the same as your current 3.5" pulley.

Would be nice, but short of modifying the belt guide it will not fit. I suspect other potential conflicts with the deck but I quit looking after the belt guide issue.


There are Canadian suppliers of the same product. These guys are in the Toronto area and it sounds like they might even be manufacturing some of this stuff to order.

H style 10mm hub: https://www.motioncanada.ca/products/sku/02167588;origin=sayt

H style 3.75" OD pulley: https://www.motioncanada.ca/products/sku/02910163

Now these guys actually spec some dimensions and I see the H style hub is 1-1/4" (32mm) thick through the bore hole. I'm concerned that might be too tall for your application -- yours is thinner through the bore --

Yes - I wondered about that.

including the bit that has to fit inside the recess. Now you could shim it up with a spacer or even some washers to clear the casting recess, but will there still be sufficient thread left for the nut on top? Will a split bushing hub tend to wobble if a substantial part of the bore is around threads instead of being firmly supported?

I wonder if this G style hub would be better, as it is only 1" through the bore:

https://www.motioncanada.ca/products/sku/08537688;origin=sayt

Am I missing something? I don't see a keyway - or is that the split on the sides seem small for that?



I didn't go hunting down a pulley for that one, but it might be worth giving these guys a call to discuss the options.

I wonder if they have a PDF catalog - that might save some chasing around.

 

[AndyM]

I should add that my concern over the hub thickness is related to where the pulley centerline ends up. The width of the pulley doesn't really matter, it's where the belt rides. It needs to be aligned with the drive pulley to avoid problems.

Yes I think that could be a problem alright.

 

[AndyM]

I printed one off in cheap PLA as a proof of concept. The overhang of the upper half of the sheave is proving a bit challenging, so I've tweaked the supports a bit and am currently printing off a second prototype. But after a bit of post-print processing with a file, it actually seems like a viable idea. Here it is running at 500 rpm or so with a 3L belt:

[video deleted because there's no way to stop autoplaying the next video in Dailymotion. I won't use them again]

If you want to watch the short video clip you can download it from here instead.

(and yes, it's driving a hand-held bicycle training wheel )

Looks great to me - I guess the question would be how it would stand up the constant start and stop and the torque loads pulling the mower (and me) up a hill...