[n1tr0]

You can see more thermal pictures in the general Mill-Turn thread, but my spindle is really noisy and runs much hotter then it should. I've also got some build quality concerns because the mounting face of it was messed up by the factory in order to 'tram' the spindle and the access hole for the pin is too small to actually do any adjustments.


I reached out to the guys who did the "how to build a CNC from scratch" thread, SkyFireCNC about getting a little higher quality spindle made. Their R8-80 spindle was almost the same size as the unit in the Mill-Turn and it comes standard setup for 6k rpm with optional 10k rpm bearings/balancing. It uses double angular contact bearings top and bottom instead of the single bearings in my Mill-Yurn. They also use an HTD style timing belt on their spindles, so I've requested a matching pulley for the stock motor with a 2:1 ratio. Right now my machine struggles/surges to reach the advertised 5k rpm (at the spindle) which is right at the ~120Hz/3600rpm upper limit @ the motor. The new 2:1 ratio should move the max rpm up to ~7k rpm without much of a drop in low-speed torque and with the timing belt, tensioning shouldn't be as finicky. I think it should fit between a 114-116 tooth 25mm wide HTD(5mm) belt.

I've also designed up a simple mounting system for SkyFIre's power-drawbar (QTC system) which I believe is compatible with the real Tormach (TTS) system. I'll be releasing my adapter design files on Thingiverse. It's already been published and licensed under the Creative-Commons-Non-Commercial-Share-alike terms.

Let me know if you're interested in participating in a group buy, there's already at least a couple others.

[BIGBLOCK1965]

Your spindle should have double angular contact bearings on top and bottom. My machine reaches about max temperature within a few minutes of running, then pretty much stays at that temperature for as long as it goes. I don't have a gauge, but I can hold my hand on it no problem. If yours is noisy and getting hot like your picture, then my guess is you have a bad bearing. Shopmaster has a 3 year warranty on parts, so I think all the units out there should still be covered. Another fellow posted about upgrading from grease filled to oil filled bearings for high rpm work. They are pretty pricey at near 300.00 each, but may be worthwhile in the long term. Grinding on the cartridge is not the proper way to tram- using shims is fast and easy, and JT has a nice file on how to do it. A note of caution on the tooth belt drives- I converted one of my earlier machines to tooth belts and it was easy to do, but they are very sensitive to alignment. A V belt can take misalignment and work fine, but a tooth belt just a bit off will want to walk off the pulley and wear the belt, plus it will make an ear-splitting whining noise at high rpm, a sound that will drive anyone nuts. I am really interested in that PDB unit as well, so PM me with the price and some specs. Your drawing doesn't show the detail, but to work properly, it cannot simply put downward pressure on the drawbar, it must support the drawbar upwards at the same time, or the pressure will destroy the top bearing in no time. The overall concept looks like an easy fit on the machine with only a little sheet metal cutout necessary to clear.

[n1tr0]

I'm aware my spindle is defective and improperly trammed by the factory, but the last time I sent something to Shopmaster for repair, it was some broken wires in the DRO and it took a full month for me to get it back, I think the lead time for a new spindle is only a bit longer and the current spindle should hopefully last that long.. I haven't taken my spindle apart, but the Norton_BMW guy did and his weren't double angular contact bearings and the part numbers he sent me match what I can read on mine.

You bring up a good point 'tho, there seems to be plenty of deviations batch-to-batch with the Mill-Turns, so I'll post all my drawings so people can confirm whether this will fit their machines. This is not something I have any financial interest in, so I don't want anyone trying to hold me accountable if this doesn't work for them. That being said, if anyone needs the adapter mounts machined, I can probably make extras on our Tormach.

We've got a Tormach PCNC 1100 with the power-drawbar at work now with the TTS system and it's just a ram pushing down on the bolt when actuated the same as SkyFire uses on their own machines. There might be a better method, but this seems to be working for a lot of people.

[BIGBLOCK1965]

Hmm- very strange, the numbers he quoted in his post are classed as Double row angular contact bearings, and the picture certainly looks a lot thicker than a single row bearing. Maybe you need to open your spindle up to be sure. I would like to see a picture of your Tormach PDB, because there has been a lot of discussion on their forum from guys designing their own, and it's universally agreed that direct downward pressure on the drawbar is a death knell for the top bearings.

Here is a link to a guy who documented the construction of a PDB for a Tormach.
Experience with the Tormach Milling Machine and Power Draw Bar

[n1tr0]

I would like to see a picture of your Tormach PDB,

Attachment 333562
Let me know if you want any specific shots of it. It sure beats wrenching to change the bits constantly.. With the Mill-Turn it always seems like the sheet metal is in the way when it's time to change bits and it's so slow moving up and down, but I'm working on that problem as well.

[BIGBLOCK1965]

Attachment 333562
Let me know if you want any specific shots of it. It sure beats wrenching to change the bits constantly..

Well it sure is putting pressure right on the end of the drawbar and the top bearing. Building one like that would be a snap, as those other styles require a lot more moving parts and extra machining. If it has been working fine for your Tormach, then maybe those other guys are just doing some of that engineering hand-wringing. So what you will be building is a mounting adapter for the Mill Turn, and then we would just buy the Tormach PDB- correct?

[BIGBLOCK1965]

[QUOTE=n1tr0;1938028] I sent in the DRO and it took a month for me to get it back,

Sorry, I missed this bit on last response. I had an intermittent problem on my DRO as well, it would work fine, then sometimes one axis would blink off. After trying a lot of tests, we could not figure it out so JT asked me to send it back so his CNC guy could check it out. It arrived at his shop just as the CNC guy went on vacation, and he said he tried it on his machine and it was working fine. Just to save time, he sent me the unit off his machine. I had it back in a few days and put it on, all was fine and then BINGO, same problem. Finally I monkeyed around with the cable from the reader and found one of the pins was slightly bent. I straightened it out and since then it has been fine. But I found a nice surprise, the new display is the upgraded version with the Lathe-Mill display swap. As I'm sure you know, the axes designations are different on lathe and mill, which is not a big problem for manual work, but with CNC, it is confusing. On the mill X axis is longitudinal and is Z in lathe, while the Y mill axis cross slide becomes X in lathe and the Z in mill becomes Y in lathe. Trying to keep all this straight while reading the display and setting zero can be really confusing. The new displays are redesigned so that all you do is push a button and the readings from the scales will go to the proper axis in either lathe or mill mode.

[n1tr0]

Here's the pdf/drawing of the spindle I have on order from Skyfire. I've requested a 30 tooth pulley instead of the 36 tho so I can pair it with a 60 tooth motor pulley for my ideal rpm range. The motor pulley will have flanges to keep the belt from walking and I plan to sandwich a thin optical encoder disk between the spindle pulley and the locknut.
Attachment 333640

[BIGBLOCK1965]

Here's the pdf/drawing of the spindle I have on order from Skyfire. I've requested a 30 tooth pulley instead of the 36 tho so I can pair it with a 60 tooth motor pulley for my ideal rpm range. The motor pulley will have flanges to keep the belt from walking and I plan to sandwich a thin optical encoder disk between the spindle pulley and the locknut.
Attachment 333640

Interesting, it looks like an identical cartridge to the Shopmaster, right down to the mounting holes- it should bolt right in place. My guess is that this is an off the shelf Chinese design from a spindle factory and the Shopmaster factory probably buys them there as well. The only difference I see is that the Skyfire uses unsealed bearings with the seals installed in the cartridge- do they run grease or oil bath? The flanges on the pulleys will prevent the belts from walking off, but unless the alignment is spot-on, you will get wear on the belt edge and that irritating whining sound, especially at 7500 rpm.

[JTJT]

There was some discussion on another thread about adapting a power drawbar to the Mill Turn, and people often ask us if we offer that as an option. We actually built an air butterfly PDB many years ago on our Bridgemill model and it worked great. However back then, there was not as much CNC work as there is now, so we have sort of revived the idea and our factory is working on some ideas for the future. There are as many designs out there as there are machinists, but not too many off the shelf units available. They come in 2 basic types-
1. Air cylinder which compresses a drawbar with a stack of belleville washers to release tension on the collet.
2. The air "butterfly" wrench which loosens and tightens the drawbar threads.
Each has its own advantages and disadvantages.

The compressing air cylinder design is more complex because it has to have a floating design to compress the belleville washers while not putting pressure on the spindle bearings. The air cylinders, valve and air fittings are available, but it takes some engineering calculations to get the proper cylinder etc. And the parts will be more expensive than the butterfly type. However, once engineered it will be a faster and lower maintenance setup. You can buy an off the shelf unit like a Tormach and adapt it to the Mill Turn, but you are looking at 1200.00, which is pretty pricey, considering you could source the parts and make all the components yourself for a few hundred dollars. Here is a simple drawing of how the Tormach unit might look on the Mill Turn.
Attachment 333720 simple idea to attach the Tormach unit

Attachment 333726 Tormach style with belleville washers

Attachment 333728 The Tormach full kit

The butterfly air wrench design is very inexpensive- there are some units on E-bay for 130.00, and one can be built for around 50.00 in parts. The concept is simple, in that the air wrench tightens and loosens the drawbar and with some calculations, it will force the collet down as the drawbar moves up and bottoms out in the socket. Some designs have a lever that you can use to pop the collet loose. However, you will need a better quality drawbar,as the threads are being loosened and tightened a lot. Eventually, the thread on the drawbar and the collet will begin to wear and need replacing. Here are some pictures of variuos styles and a link to a how to build thread.
Attachment 333722 E-Bay unit for 130.00

Attachment 333724 DIY design for 50.00

Here's the link for DIY units
CNC Cookbook: Powered Drawbar for IH Mill

[n1tr0]

If you're going to take my pictures and drawings, it would be nice if you could get the information correct. This would be better posted in the existing thread.

[JTJT]

If you're going to take my pictures and drawings, it would be nice if you could get the information correct. This would be better posted in the existing thread.

Not sure what is incorrect about the post, and there is no other thread specifically about power drawbars for the Mill Turn. BTW- all those pictures and hundreds of others are on Google images- as I said, there are as many different designs out there as there are machinists.

[n1tr0]

Not sure what is incorrect about the post, and there is no other thread specifically about power drawbars for the Mill Turn. BTW- all those pictures and hundreds of others are on Google images- as I said, there are as many different designs out there as there are machinists.

The first picture you used is of the CAD model I designed and posted in this thread for retrofitting a SkyFireCNC QTC/Power-Draw-Bar onto a Mill-Turn, not a Tormach unit. The files required for others to make the adapter are published and licenced on Thingiverse under the Creative Commons, Non-Commercial, Share-alike licence, which means anyone can use/modify the design assuming they also share their derivative design and it is not resold for commercial purposes. Anyone needing the design files in a specific format can contact me PM.
Also The SkyFireCNC QTC system is already engineered with all the correct forces and they quoted me ~$300, not $1200. The nice thing with their stuff is that it really is TTS compatible unlike the "TTS-style holders" that shipped with my Mill-Yurn. A collet holder in a collet holder isn't what makes the TTS tool holders work, it's the pre-loaded shoulder contact with the face of the spindle which makes the tool holders more rigid and the height repeatable.

The second picture is not a Tormach-like kit, it's a photo I took of an actual Tormach PDB on a PCNC 1100 minutes after BigBlock asked about it.

Pretending like you just stumbled across my images on Google is a little insulting and quite unprofessional.

[JTJT]

[QUOTEPretending like you just stumbled across my images on Google is a little insulting and quite unprofessional.[/QUOTE]

Here's the link- scroll on down and you will find all the pictures and many more
https://www.google.com/search?safe=a...k1.T9V2WwbsUqY

[instructor37]

There was some discussion on another thread about adapting a power drawbar to the Mill Turn, and people often ask us if we offer that as an option. We actually built an air butterfly PDB many years ago on our Bridgemill model and it worked great. However back then, there was not as much CNC work as there is now, so we have sort of revived the idea and our factory is working on some ideas for the future. There are as many designs out there as there are machinists, but not too many off the shelf units available. They come in 2 basic types-
1. Air cylinder which compresses a drawbar with a stack of belleville washers to release tension on the collet.
2. The air "butterfly" wrench which loosens and tightens the drawbar threads.
Each has its own advantages and disadvantages.

The compressing air cylinder design is more complex because it has to have a floating design to compress the belleville washers while not putting pressure on the spindle bearings. The air cylinders, valve and air fittings are available, but it takes some engineering calculations to get the proper cylinder etc. And the parts will be more expensive than the butterfly type. However, once engineered it will be a faster and lower maintenance setup. You can buy an off the shelf unit like a Tormach and adapt it to the Mill Turn, but you are looking at 1200.00, which is pretty pricey, considering you could source the parts and make all the components yourself for a few hundred dollars. Here is a simple drawing of how the Tormach unit might look on the Mill Turn.
Attachment 333720 simple idea to attach the Tormach unit

Attachment 333726 Tormach style with belleville washers

Attachment 333728 The Tormach full kit

The butterfly air wrench design is very inexpensive- there are some units on E-bay for 130.00, and one can be built for around 50.00 in parts. The concept is simple, in that the air wrench tightens and loosens the drawbar and with some calculations, it will force the collet down as the drawbar moves up and bottoms out in the socket. Some designs have a lever that you can use to pop the collet loose. However, you will need a better quality drawbar,as the threads are being loosened and tightened a lot. Eventually, the thread on the drawbar and the collet will begin to wear and need replacing. Here are some pictures of variuos styles and a link to a how to build thread.
Attachment 333722 E-Bay unit for 130.00

Attachment 333724 DIY design for 50.00

Here's the link for DIY units
CNC Cookbook: Powered Drawbar for IH Mill

One thing you forgot about the butterfly style design is that the socket on the butterfly is usually in constant contact with the drawbar, meaning that when the spindle is turning, the butterfly wrench spindle is also turning, and that fairly loose connection between the socket and the drawbar will be pretty loud at higher rpm's.

[instructor37]

You can see my spindle is really noisy and runs much hotter then it should.

Not sure how we ended up over here, but I think I can see where your spindle problem is. From the image, all your heat is generating from the lower bearing. it could be something as simple as a seal that was damaged at installation or even dented while installing a tool. The seals run on the inner race, and if they get bumped, it is a very close distance to the cage that retains the balls. If the seal is hitting the cage, it will generate a lot of heat and also be noisy. I would inspect that bottom seal very closely. As an upgrade, I would go with a pair of single seal bearings, with the unsealed sides on the inside of the cartridge like the Skyfire where there is no chance of contamination. This would reduce the seal friction and heat by 50%. Happily, the single sealed bearings in the same quality are less expensive than the double seals- around 35-40.00 each. You could easily end up with a 7K capable spindle for 70-80.00 and an hour or two of labor.
Attachment 333742

[n1tr0]

Not sure how we ended up over here, but I think I can see where your spindle problem is. From the image, all your heat is generating from the lower bearing...

You might be reading too much into the one image. The upper 2/3'rds of the spindle is hidden inside the beam and behind the sheet-metal shroud. The seals look fine from the outside, I have more pictures of those. This has been a problem since I got the VFD working. There is a good chance it may have been assembled/pressed together incorrectly 'tho, there were other problems with it. The dowel pin for the collet was set too deep when I got it, the hole for adjusting that pin was undersized, and instead of shimming the spindle, they appear to have used an angle-grinder on it's mounting face...

I'll definitely take it apart and see what can be done once I have a replacement from Skyfire. I'd like to keep the machine as functional as possible while I sort out all the other problems, like replacing the controller, the motors, getting the belts & pulleys sorted, etc. Now that we have a Tormach at my workplace, I can start fixing some of these parts. It's really hard to fix your mill at home without a working mill...

[instructor37]

[QUOTE

I'll definitely take it apart and see what can be done once I have a replacement from Skyfire. I'd like to keep the machine as functional as possible .[/QUOTE]

Yeah, I think I would look into it before dropping 500.00 on a new spindle- might be able to upgrade it for the cost of a couple bearings and still get your 7K rpm to boot.