# What cutters to use for custom micro-v pulleys?



## robotwizard (Apr 13, 2018)

Need to make some Micro-v multigroove pulleys for 6 groove wide belts. Will likely use aluminum. Page 41 of Gates design manual 

https://ww2.gates.com/europe/file_s...file=20070_E2_V-BELTS_DRIVE_DESIGN_MANUAL.pdf 

says groove for the PJ "Micro-V" belt should be 40 degrees. What options are best tooling/cutter to use to cut the grooves?

Thanks.


----------



## Hawkeye (Apr 13, 2018)

I ground one out of a 1/4" HSS blank, similar to an acme thread-form. Just match it to the belt or the existing pulleys. Square it up good with the workpiece and get it exactly on centre. Feed in to depth then step over the same amount as on the belt or other pulley. With your indicator set to zero at the proper depth, the grooves will all be the same.


----------



## 4GSR (Apr 14, 2018)

Tool-flo sells ground full profile inserts for any pitch of the poly-groove sheave configuration out there.  They are not cheap.  The last sheave I cut, ground mine, too.

http://www.toolflo.com/catalogs/AUTOMOTIVE.pdf


----------



## Cobra (Apr 14, 2018)

Hawkeye said:


> I ground one out of a 1/4" HSS blank, similar to an acme thread-form. Just match it to the belt or the existing pulleys. Square it up good with the workpiece and get it exactly on centre. Feed in to depth then step over the same amount as on the belt or other pulley. With your indicator set to zero at the proper depth, the grooves will all be the same.



Same as Mike.  Ground a HSS tool to match and cut each groove individually. Use for the waterpump drive on the Cobra.


----------



## GoceKU (Apr 14, 2018)

I have a project where i have to make Micro-v multi groove pulleys one in steel other in aluminium, my plan is to start with grounding a HSS cut off tool if that doesn't work to try to ground carbide cut off insert and use it, keep us updated how you make out.


----------



## Ray C (Apr 14, 2018)

I made two 4" diameter sheaves not long ago for a micro-V and roughed it out with a DCMT carbide tool and finished with a hand ground HSS.   The belt fits very well.  In the process of this, I discovered that not all belts are created equal.   I had equivalent sizes from two manufacturers.  The Gates belt fit the profile very well.  The no-name brand had a very different profile that ultimately worked but, it also had a "heavy" or "thick" part in the backbone that caused noticeably more vibration.  -Just a junky belt I guess...

Ray


----------



## robotwizard (Apr 15, 2018)

Thanks for the replies. There are so many variables related to tooling, makes it a bit overwhelming for a beginner. I ordered a 1/4" tooling blank, but will it work for 6061 alum? Will the DCMT carbide inserts work for aluminum, or should I get something else? Was hoping to start out with carbide inserts and learn how to grind HSS tooling later just to keep things simple at first. Shars and other catalogs do have some reference pages for inserts, but I think I need a more basic reference to start out. I have an AXA quick change TP and some extra holders. Need to get a basic set of toolholders some inserts, but there are so many angles and shapes...


----------



## Ray C (Apr 15, 2018)

robotwizard said:


> Thanks for the replies. There are so many variables related to tooling, makes it a bit overwhelming for a beginner. I ordered a 1/4" tooling blank, but will it work for 6061 alum? Will the DCMT carbide inserts work for aluminum, or should I get something else? Was hoping to start out with carbide inserts and learn how to grind HSS tooling later just to keep things simple at first. Shars and other catalogs do have some reference pages for inserts, but I think I need a more basic reference to start out. I have an AXA quick change TP and some extra holders. Need to get a basic set of toolholders some inserts, but there are so many angles and shapes...



What lathe do you have?   These are some good starter sets. 

First link is for a 3/8" shank set.  It's on sale now.  Perfect for an AXA.
https://www.ebay.com/itm/SHARS-7PCS...972823?hash=item1ca79a0397:g:OKQAAOSwkrFagcTe

This is the same set as above but 1/2" shank.  These will fit your AXA holders but may be too big for your lathe.

https://www.ebay.com/itm/SHARS-1-2-...166083?hash=item4602f2a103:g:PcAAAOSwcBhWU1kt


This set is great, sold by a friend of mine and sponsor of this web site.  These are different inserts than above but unlike the sets above, all the insert holders take the same insert which is VERY convenient.   This is my preferred recommendation from a technical perspective but, they are a little more expensive. 

Here's a 3/8" set.
http://www.precisionmatthews.com/sh...ool-set-sized-for-axa-quick-change-tool-post/

Here's a 1/2" set.
http://www.precisionmatthews.com/sh...ool-set-sized-for-bxa-quick-change-tool-post/

Yes, a DCMT can cut aluminum.


Ray


----------



## Hawkeye (Apr 16, 2018)

Keep in mind that the angles you need for multi-groove pulleys may not be available in carbide inserts, at least at a hobby level. HSS is a lot easier to grind and actually cuts better than carbide. If the 6061 is sticking to the cutter, try a shot of WD40, kerosene or brush on a bit of Crisco.


----------



## Bob Korves (Apr 16, 2018)

robotwizard said:


> Need to make some Micro-v multigroove pulleys for 6 groove wide belts. Will likely use aluminum. Page 41 of Gates design manual
> 
> https://ww2.gates.com/europe/file_save_common.cfm?thispath=Europe/documents_module&file=20070_E2_V-BELTS_DRIVE_DESIGN_MANUAL.pdf
> 
> ...


Do not over think this.  The first response to the thread is entirely useful, and the others as well.  High speed steel will work for aluminum, mild steels, and most anything that is not hardened.  Grind a tool with proper relief and clearance, a slight flat on the end, like a threading tool except for the angle, and get to cutting.  DCMT carbide inserts are 55 degrees, so you would still need to finish the cuts with HSS or grind the carbide to a different angle, not easy without diamond grinding wheels.


----------



## ChrisAttebery (Apr 16, 2018)

I just cut a set of Micro(Poly) V pulleys last month. I'm a die hard carbide user but I opted to use a ground HSS tool. It worked like a charm. Cut a groove, step over .092", repeat.


----------



## robotwizard (Apr 18, 2018)

Lathe is a PM-1127.  Have a 1.5hp marathon motor with 1000:1 torque to upgrade from the original 1hp, but not installed yet. Would 3/8" or 1/2" shank be better?

Looks like the Ebay set was a good buy, but unfortunately I got there too late.

Matts site says sets are on backorder




Ray C said:


> What lathe do you have?   These are some good starter sets.
> 
> First link is for a 3/8" shank set.  It's on sale now.  Perfect for an AXA.
> https://www.ebay.com/itm/SHARS-7PCS...972823?hash=item1ca79a0397:g:OKQAAOSwkrFagcTe
> ...


----------



## Ray C (Apr 18, 2018)

robotwizard said:


> Lathe is a PM-1127.  Have a 1.5hp marathon motor with 1000:1 torque to upgrade from the original 1hp, but not installed yet. Would 3/8" or 1/2" shank be better?
> 
> Looks like the Ebay set was a good buy, but unfortunately I got there too late.
> 
> Matts site says sets are on backorder



You could go either way but most "hobby-level" lathes with 14" swing and under, are not designed for hogging.  With 1/2", all your toolpost holders will need to be adjusted about as low as they can go.  With 3/8, you might have an occasional (rare) problem if you ever need to extend the tool to reach a cut.   If I had no plans to ever upgrade to a larger lathe, from 11" swing, I personally would go with 3/8".  It's appropriately sized and won't get in the way of your setups.  As time passes, you could get a few 1/2" shanks to handle the fewer situations when extra stick-out is needed.   In all reality, when you need extra stick-out, you probably need to re-think the setup and how you're approaching that cut.   Anyhow,  if you think you might upgrade to a 12 or 14" lathe, then go with 1/2".

A quick question:  Why are you upgrading the motor on the lathe?   1 HP is plenty for an 11" swing lathe.  You'll never be able to utilize the extra power because the rest of the machine will be subjected to undue stress.

Ray


----------



## cjtoombs (Apr 18, 2018)

I would try the form ground cutter mentioned above and go stright in, cutting on both sides of the tool, as a first pass.  If your lathe isn't up to the task, you will get chattering.  If that happens, grind one side of the tool with a bit of relief and feed it in at half the included angle with the compound (20 degrees in this case) with the 20 degree side of the tool doing the cutting.  Make sure the tool is still square with the worrk.  That should help with any chattering.  Unless you have a very light lathe, I wouldn't expect any problems with the straight in method with those shalow groves in aluminum.


----------



## robotwizard (Apr 24, 2018)

Ray C said:


> You could go either way but most "hobby-level" lathes with 14" swing and under, are not designed for hogging.  With 1/2", all your toolpost holders will need to be adjusted about as low as they can go.  With 3/8, you might have an occasional (rare) problem if you ever need to extend the tool to reach a cut.   If I had no plans to ever upgrade to a larger lathe, from 11" swing, I personally would go with 3/8".  It's appropriately sized and won't get in the way of your setups.  As time passes, you could get a few 1/2" shanks to handle the fewer situations when extra stick-out is needed.   In all reality, when you need extra stick-out, you probably need to re-think the setup and how you're approaching that cut.   Anyhow,  if you think you might upgrade to a 12 or 14" lathe, then go with 1/2".
> 
> A quick question:  Why are you upgrading the motor on the lathe?   1 HP is plenty for an 11" swing lathe.  You'll never be able to utilize the extra power because the rest of the machine will be subjected to undue stress.
> 
> Ray



Thanks. My motivation for the motor upgrade isn't to increase horsepower. Besides replacing the no-name oem motor with a higher quality unit that will last, the Marathon will provide constant torque all the way down to zero rpm. I've seen videos where guys can grab the chuck and stop the motor at low rpm settings with this particular lathe with the original motors.  The upgraded motor/vfd will also interface better for computer control of spindle for threading and constant sfm when I do the cnc conversion at some future time . I was looking for a motor to upgrade my PM727 mill for the belt conversion to be able to run the spindle at 5k for small cnc cutters, while maintaining low speed torque for larger cutters etc.  I ran across these 1.5hp inverter duty 1000:1 motors that were new surplus at a fraction of new cost. They had 2 left, so I decided to get one for the lathe as well.


----------



## robotwizard (Apr 24, 2018)

cjtoombs said:


> I would try the form ground cutter mentioned above and go stright in, cutting on both sides of the tool, as a first pass.  If your lathe isn't up to the task, you will get chattering.  If that happens, grind one side of the tool with a bit of relief and feed it in at half the included angle with the compound (20 degrees in this case) with the 20 degree side of the tool doing the cutting.  Make sure the tool is still square with the worrk.  That should help with any chattering.  Unless you have a very light lathe, I wouldn't expect any problems with the straight in method with those shalow groves in aluminum.



Thanks cjtoombs, I will give that a try.


----------



## Ray C (Apr 25, 2018)

robotwizard said:


> Thanks. My motivation for the motor upgrade isn't to increase horsepower. Besides replacing the no-name oem motor with a higher quality unit that will last, the Marathon will provide constant torque all the way down to zero rpm. I've seen videos where guys can grab the chuck and stop the motor at low rpm settings with this particular lathe with the original motors.  The upgraded motor/vfd will also interface better for computer control of spindle for threading and constant sfm when I do the cnc conversion at some future time . I was looking for a motor to upgrade my PM727 mill for the belt conversion to be able to run the spindle at 5k for small cnc cutters, while maintaining low speed torque for larger cutters etc.  I ran across these 1.5hp inverter duty 1000:1 motors that were new surplus at a fraction of new cost. They had 2 left, so I decided to get one for the lathe as well.



Sounds pretty cool then.  Take pictures and let us see how it's working out.   What kind of controller will you use with it?

Did you finally get some tool holders?

Ray


----------



## jbolt (Apr 25, 2018)

I agree with Bob. Don't over think it. I have made on the order of two dozen or more micro-v step pulley sets for people for belt drive spindle conversions. I use a HSS T-Type cut-off blade ground to 40 degrees with a lightly blunted point. Works like a champ. The angle doesn't have to be perfect just close.


----------



## rowbare (Apr 27, 2018)

The thing you need to be mindful of is that even though you have constant torque down to very low speeds, you have next to no horsepower at those low speeds. Horsepower is a function of torque and speed so if you motor is rated at 1.5hp at 1800 rpm, it is only putting out .15 hp at 180 rpm whereas if you use mechanical reduction to get down to that speed you still have 1.5 hp. 

Why is this significant? Because Metal Removal Rates are a function of HP. So if you use mechanical means to get to 180 rpm, you can hog like crazy. If you use a VFD to get to 180 rpm not so much; in fact you can only remove about 1/10th of the metal per unit time. That gets old really fast.

One way to get around this is to use a much larger motor than seems appropriate for the size of the machine. The extra power doesn't do much for you at the upper end due to machine limitations but will help you a lot at lower speeds. Also it is a good idea to have two speed ranges, a high range for normal use and a low range for threading and large diameter stock.

bob


----------



## P. Waller (May 3, 2018)

rowbare said:


> The thing you need to be mindful of is that even though you have constant torque down to very low speeds, you have next to no horsepower at those low speeds.
> 
> bob


What he said. Work Over Time

Horsepower + Torque in Ft. Lb's. X RPM/5252


----------

