Ye Olde Comm Lathes: Need Some Info...

[crawlinwithacat]

I have decided to get into comm cutting and need some information on some specific lathes. I know that it is a quite outdated area of the hobby, and I know a lot of you will probably laugh at me, but I think that the process could be quite valuable to me as a crawler person that typically uses rebuildable brushed motors. I stumbled across a lathe for sale the other day and had no clue what it was supposed to be used for but after some research I thought it was the coolest thing and decided it could be something fun to try. (I mean we're all just stuck at home right?:ror I have already done many hours of research on the topic and have learned much about the nuances of comm cutting; stock vs modified, bearing vs V-groove, diamond bit vs carbide bit, etc.

So the first thing I need to know is: Can the Orion Daren's Quick Set Lathe cut both 540 AND 550 size armatures? Or just 540...

Second thing: Does anybody have an XIPP Perfect Lathe 2 that they would be willing to sell? The Reason I ask about this one is that it can turn 130-550 size armatures which is great, and I would choose it over the Orion if I could, however I have not been able to find one for sale anywhere.

Hopefully one of the veterans around here can see this and help a girl out. Thanks for looking! Cheers!8)

 

[Big Bill]

I have cut a lot of comms. over the past 50 years. I still like a brushed motor over the brushless setup of today, it is fun to re fresh a motor and have it perform well. A few tips are to use a black sharpie to color the comm. and see the cut you are making. I used a variable power supply on mine so I could change the speed of the cutter to get the speed right so it would have a clean cut. Start be taking really small cuts and work your way up until the comm. is clean. If you can get new bits for your lathe start with a good one and make sure it is installed in the correct position so it does not gouge the surface. Brushes and springs I would think you can still get them from somebody, it fun hope this helps."thumbsup"

 

[crawlinwithacat]

I have read that a sharpie is one of the tricks. And it makes sense. Being a woodworker when I sharpen my chisels and gouges I put sharpie on the bevel to make sure I have good contact. Same idea I guess. A variable power supply is a fantastic idea! I already have one that I got for some anodizing experiments a couple years back. I have already looked at replacement bits and a replacement AL- or AR-4 of good quality with and indexable carbide cutting head will only set me back 20-30 bucks. I was surfing around HH and found that they carry replacement brushes, armatures, brush channels, brush hoods, endbells, etc for their rebuildable motors which is great to know. Thanks for sharing some of your wisdom!"thumbsup"

 

[Big Bill]

For sure, and Thank You for mentioning HH for motor parts completely forgot about him. There are also different spring tensions to get what you want out of a motor, I cant recall how they work but you can change the spring to get different RMP figures, same deal with changing the timing with the endbell.

 

[crawlinwithacat]

For sure, and Thank You for mentioning HH for motor parts completely forgot about him. There are also different spring tensions to get what you want out of a motor, I cant recall how they work but you can change the spring to get different RMP figures, same deal with changing the timing with the endbell.

I feel like I watched a video the other day and they mentioned something about spring strength. I will have to look into it. Then I know people adjust the endbell for different performance reasons, and like you said rpms, but I couldn't start to explain it. Looks like something new to learn about!

So then i have another question for you. More of a scenario really. I have located a good deal on a lathe. $85 for the lathe, brush hood alignment tool, some other misc tools, carbide bit, and oil. Thing is, i don't know if it will turn 540 and 550 armatures. I am pretty confident it will turn 540s, the 550 is the question. Right now i have 4 540 motors and 1 550 motor so a ratio of 4:1. So is the lathe worth that gamble if I predict that I will maintain that raito of 4:1 in the future? What do you think? Do you think it's worth not being able to turn that one motor? Or would you wait to find one that would do exactly what you want... Here's the link to the one I'm looking at:
Team Orion Daren's Quick Set Motor Lathe

Sorry, hopefully that's not too confusing, that is just my current dilemma and would like a second person's opinion on it.

 

[Gula]

I remember usung a ballpoint pen to run between the groves of the comm to remove any sharp edges

 

[crawlinwithacat]

I remember usung a ballpoint pen to run between the groves of the comm to remove any sharp edges

Yes, I read that as well and it sounds like a great trick"thumbsup"

 

[calvinn]

You might find this interesting:

https://www.hobbytalk.com/threads/rc-motor-black-book.126994/

 

[bbrigg]

JRH on rebuilding brushed motors. Has some good information on comm Lathe.

https://youtu.be/9y-e1gq_YS0

~more facts, logic and personal responsibility would make the world a far better place than all the leftist ideas could dream of.

 

[crawlinwithacat]

You might find this interesting:

https://www.hobbytalk.com/threads/rc-motor-black-book.126994/

Lots of info there! I scrolled down to the comm cutting section and there was some good info there. I will look around on fleabay and see if I can maybe find one of those books

JRH on rebuilding brushed motors. Has some good information on comm Lathe.

https://youtu.be/9y-e1gq_YS0

~more facts, logic and personal responsibility would make the world a far better place than all the leftist ideas could dream of.

I watched it, he didn't say as much about the comm lathe as I thought he would. i thought it was interesting that at the end he said that he doesn't recommend breaking in motors in water.

Thanks for the resources you guys!

 

[Robbob]

Loys of info and pictures in this old thread, Def worth a reading.

http://www.rccrawler.com/forum/electronics/223989-cutting-motor-commutator-motor-tweaks.html

Theres also Brood for brushed motor parts Teambrood

Lots of parts for anything you need plus Eddie really knows how brushed motors work for any application.

 

[crawlinwithacat]

Loys of info and pictures in this old thread, Def worth a reading.

http://www.rccrawler.com/forum/electronics/223989-cutting-motor-commutator-motor-tweaks.html

Theres also Brood for brushed motor parts Teambrood

Lots of parts for anything you need plus Eddie really knows how brushed motors work for any application.

I scrolled through a couple pages of that thread, I think I've been to it at least a dozen times in the last week or so lol. I've been thinking about getting a motor or 2 from team brood for my Gelande II; still has the stock motor in and is feeling a little weak.

In other news, I have decided to buy the Team Orion lathe:mrgreen: The deciding factor was actually that I noticed it had 30 day returns so If I am not happy with it, I can send it on back. I will post pics when I get it"thumbsup"

:idea:Still open to any more knowledge, thoughts, or wisdom to anyone that might have it

 

[crawlinwithacat]

The postman came by yesterday and dropped off my new comm lathe! I have not gotten a chance to test it out or turn it on but I will hopefully do that this weekend and report back. For now, here are some pictures of the lathe. I received a small bottle of oil, a brush hood alignment tool, a couple motor shafts, the o-ring, a small hex driver and something else I can't identify (last picture). It appears to be for measuring something but I'm not sure what. It is also spring loaded, has a small V-grove in the long end, and is numbered 0-10. Maybe somebody here can tell me?

I also plan to make a thread specific to this lathe with as much info as I can because I had such a hard time finding specs and information on it before I made the purchase. I figured I would do the next person a favor and compile what I know and will learn through using the lathe into a one-stop shop of knowledge. Cheers!

 

[calvinn]

The last item is a "fiddlestick". It is used for measuring the motor brush spring tension (for comparative purposes). Covered extensively in Big Jim's Black Book. Readings are in 'fiddlesticks' i.e. a spring will have a fiddlestick value of 6.5, etc. Oftentimes the + spring will have a different value than the - spring. Motor spring tension can be important for comm life and performance.

 

[crawlinwithacat]

The last item is a "fiddlestick". It is used for measuring the motor brush spring tension (for comparative purposes). Covered extensively in Big Jim's Black Book. Readings are in 'fiddlesticks' i.e. a spring will have a fiddlestick value of 6.5, etc. Oftentimes the + spring will have a different value than the - spring. Motor spring tension can be important for comm life and performance.

Oh! I got you. Thanks! That reminds me, I should have a look around for one of those books...

 

[crawlinwithacat]

I was able to turn a comm this weekend and the lathe is my new favorite tool and turning comms is an awesome experience! Everything went very smoothly, I took Big Bill's suggestion of using a variable power supply which worked superbly and I will have a BEC set up in the future so I can run it off a lipo when in the field. I am quite familiar with turning/ resurfacing things because I turn a lot of brake rotors at the auto shop I intern at (My high school has an internship program) so the process was not new. No real issues arose, I did get some chatter if I advanced the bit too fast into the cut but that is easily mitigated by slowing the cut. I also got chatter when moving back across the comm after the cut pass. Not sure why but I will experiment as I have more comms to turn. I only had one motor that actually needed turning so I decided to save that one for YouTube and tear apart a dead sealed can to practice on instead. Overall very happy and this was a great purchase!

Now, I hope nobody thinks I'm dragging this thread on longer than it needs to be (please let me know if I am) but I want to share my endeavors in terms of comm turning. With that said, I am so in love with my new lathe that I was convinced that it needed a nicely made case. Unfortunately very few of those tend to exist online anymore so I had to improvise. I took a contractor box from a Bosch jigsaw (I was elated that my dad let me use it) and built some foam inserts for the lathe, 6 motors, 3 comms (can be expanded), and in the future, a couple motor tubes and other miscellany if need be. I am mostly happy with it, doesn't look the best but hey, function over fancy right;-) I am also going to have a full set of tools for doing motor service in the box as well so that I can just pick up the case and have everything I need right there.

My dad and I are going to design a new baseplate for the lathe so that it can turn 550 motors as well. Basically just moving one of the shaft supports farther from the other to accommodate the wider arm. Then we will send out to have it machined and maybe I will anodize it myself. We'll see. I have done some anodizing experiments in the past but had a hard time getting the results consistent.

Hopefully this has been interesting... have a great day y'all!8)

 

[calvinn]

To reduce the chatter I would advise cutting in one direction only (most lathe bits are designed with this in mind and depending on the lathe you will need a left hand or right hand bit). Take more very thin cuts rather than a few thicker cuts. Cut from the edge of the comm toward the stacks, turn off the lathe when you have cut far enough in that direction, retract the bit slightly and return to the origin then reposition the bit for another thin pass. Most lathes have graduations marked on the wheel so that you can judge the relative depth of each cut. Make sure the bit is correctly positioned relative to the centerline of the shaft. I haven't cut a comm in a long time so you need to research this a little as I don't remember the fine points of this adjustment off the top of my head. This adjustment is made by putting thin shims under the bit. Also it is important to use the red sharpie on each pass as the ink serves a double function as a lubricant (this is the only lubricant needed). You know when you're successfully finished when there is no residual ink left on the comm after a skim. Rate of feed is also important and again you need to research this as I don't remember off the top of my head (the link I posted above to Big Jim's Black Book should be of help in this regard).

Couple of things I noted from your pictures. Put a drop of oil in the notches of your lathe arm supports before putting in the arm (cheap automobile oil works fine). If you gall the arm supports, you will have, for all practical purposes, trashed your lathe. Check the arm shaft in the areas that will be in contact with the V grooves for any imperfections that could damage the grooves and polish up as necessary. These procedures are especially important if the supports are aluminum as opposed to carbide. I would also put a teflon washer on the arm shaft where it butts up to the arm support to reduce any friction in this area.

 

[crawlinwithacat]

To reduce the chatter I would advise cutting in one direction only (most lathe bits are designed with this in mind and depending on the lathe you will need a left hand or right hand bit). Take more very thin cuts rather than a few thicker cuts. Cut from the edge of the comm toward the stacks, turn off the lathe when you have cut far enough in that direction, retract the bit slightly and return to the origin then reposition the bit for another thin pass. Most lathes have graduations marked on the wheel so that you can judge the relative depth of each cut. Make sure the bit is correctly positioned relative to the centerline of the shaft. I haven't cut a comm in a long time so you need to research this a little as I don't remember the fine points of this adjustment off the top of my head. This adjustment is made by putting thin shims under the bit. Also it is important to use the red sharpie on each pass as the ink serves a double function as a lubricant (this is the only lubricant needed). You know when you're successfully finished when there is no residual ink left on the comm after a skim. Rate of feed is also important and again you need to research this as I don't remember off the top of my head (the link I posted above to Big Jim's Black Book should be of help in this regard).

Couple of things I noted from your pictures. Put a drop of oil in the notches of your lathe arm supports before putting in the arm (cheap automobile oil works fine). If you gall the arm supports, you will have, for all practical purposes, trashed your lathe. Check the arm shaft in the areas that will be in contact with the V grooves for any imperfections that could damage the grooves and polish up as necessary. These procedures are especially important if the supports are aluminum as opposed to carbide. I would also put a teflon washer on the arm shaft where it butts up to the arm support to reduce any friction in this area.

Thanks for all the great info! I will check the centerline of the bit, I figured that for just mucking around with a non-critical comm it would be plenty good enough. I did put drops of oil where the shaft rides in the supports, and I will also check to see if it appears to be galled at all. Teflon washers sound like a good idea as well. And I shall heed your advice on cut direction. Thanks again!"thumbsup"

 

[EddieO]

That's actually a Trinity Spring Thing...not a Sonic Fiddlestick...works similar though.

If you have a diamond bit, you should be able to cut both ways....we all did with them in the racing days, including Mike Reedy, Jim Dieter, Oscar Jansen....all some of the greatest motor guys in RC. If its carbide, you will wanna stick to one way cutting because of how the edge is on the bit. They do dull over time, so its wise to get extras unless you have a way to resharpen it....a diamond bit cures all of this.

The sharpie is not overly needed...its a good reference to make sure you got everything, but so is just looking with your eyes....I cut 100s of comms each month, and I cannot remember the last time I used a sharpie....

You want the bit on center or just a SLIGHT amount above it...below is bad and you will get chatter which results in bad cuts.

When expanding the lathe for 550, you need to put some way to make sure the movable tower is square and parallel to the stationary side. Even the slightest bit off will cause the arm to run crooked, which result in bad cuts and accelerated wear on the shaft grooves......you will also need to make a longer pulley for the drive motor, as you really wanna keep the oring towards the center of the arm.

I have to ask, what is the white stuff on the comm tabs? Hopefully that was not added after the motor was made....

Later EddieO

 

[crawlinwithacat]

That's actually a Trinity Spring Thing...not a Sonic Fiddlestick...works similar though.

If you have a diamond bit, you should be able to cut both ways....we all did with them in the racing days, including Mike Reedy, Jim Dieter, Oscar Jansen....all some of the greatest motor guys in RC. If its carbide, you will wanna stick to one way cutting because of how the edge is on the bit. They do dull over time, so its wise to get extras unless you have a way to resharpen it....a diamond bit cures all of this.

The sharpie is not overly needed...its a good reference to make sure you got everything, but so is just looking with your eyes....I cut 100s of comms each month, and I cannot remember the last time I used a sharpie....

You want the bit on center or just a SLIGHT amount above it...below is bad and you will get chatter which results in bad cuts.

When expanding the lathe for 550, you need to put some way to make sure the movable tower is square and parallel to the stationary side. Even the slightest bit off will cause the arm to run crooked, which result in bad cuts and accelerated wear on the shaft grooves......you will also need to make a longer pulley for the drive motor, as you really wanna keep the oring towards the center of the arm.

I have to ask, what is the white stuff on the comm tabs? Hopefully that was not added after the motor was made....

Later EddieO

Spring thing... I mean that's basically what I called it when I picked it up. Has a spring? It's a spring thing!:ror:

I was thinking about getting a bit with an indexable cutter and using this one as a backup.

The thing a sharpie helps with for me is seeing when I contact the comm with the bit.

Yeah I am not sure how exactly we will solve that problem yet lol. How much error are you thinking? 1-2 thou or under 0.5 thou? Do you have any ideas? The longer pully is a good point too. I didn't think about that initially. Thanks for your input!

Oh and I have no clue what that gunk is. Some sort of glue to hold the plastic fan onto the arm (which I have ripped off in that picture since the motor was junk anyway)