TEDROCKZ
I wanna be Dave
EP and Shelby are most likely right on the bit. I overlooked that at first. Hit me with a pm and I hook you up with a bit.
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Cutting a motor commutator & motor tweaks
- Thread starter EeePee
- Start date
EddieO
I wanna be Dave
Ditch the bit and get a good carbide solid tip bit. I am simply not a fan of those type of bits on a pit lathe. We already have enough play over a normal lathe, that adding another potential source is not my cup of tea...
Make sure the bearings are nice and clean....and you REALLY need to monitor them. Chatter is bad....think like really huge fat girl on a trampoline bad.
Later EddieO
Make sure the bearings are nice and clean....and you REALLY need to monitor them. Chatter is bad....think like really huge fat girl on a trampoline bad.
Later EddieO
binaryterror
I wanna be Dave
I have currently about 15 various motors from when I was using cheap integy arms in TI and KR cans. Most coming from a local racer who was sponsored and some of these motors/arms were built or maintained by Jim Dieter. Either way, plenty to play with.
I've cut my fair share in the past, but this lathe is so much better so far.
Appears to be cutting debris somewhat tarnished on them. I'll be cleaning those up, didn't even honestly look at them until you mentioned it. They spin great, but those 2 are dirty on the roller side.
You got PM!
My Trinity has a solid carbide bit, that was one area why I was so lost with this bit. Originally I thought the black piece was the bit but its been chewed to crap. My 10+ yr old carbide bit still seems clean and problem free. Maybe I'll see how it fits.
There was no chatter on that cut, but I'll get those 2 outer rollers cleaned. They spin very well and are lubricated.
binaryterror
I wanna be Dave
Huge thanks to TEDROCKZ, he well rocks!
I got 3 sample comms cut and amazing...ahh just like in the old days. Guess it is like riding a bike.
Now after they are all cut and I cleaned the slots in the comm with the back end of an xacto...we used to score the slots with a ball point pen to round over the slots and prevent hang ups (least that what I was told to do many moons ago) - Do we still do that?
I got 3 sample comms cut and amazing...ahh just like in the old days. Guess it is like riding a bike.
Now after they are all cut and I cleaned the slots in the comm with the back end of an xacto...we used to score the slots with a ball point pen to round over the slots and prevent hang ups (least that what I was told to do many moons ago) - Do we still do that?
Charlie-III
I wanna be Dave
I still do it, don't know if JRH or Eddie still do it.:roll:8)
I will say I only "lightly" use the pen, I just want to make sure I didn't leave a "ridge" from cleaning the slot.8)
Old habits die hard........
TEDROCKZ
I wanna be Dave
Glad the bit worked for you Jake. Nothing like the right stuff for the job"thumbsup"
The pen deal is ok but not really needed. A revolutions of running will clear any micro edges left almost instantly. Especially after a proper comm turning"thumbsup"
The pen deal is ok but not really needed. A revolutions of running will clear any micro edges left almost instantly. Especially after a proper comm turning"thumbsup"
EddieO
I wanna be Dave
I am not a fan of the pen trick....it often is done wrong with too much pressure, which results in the slots getting rounded, which leads to the slots acting like a pot hole in the road....
Later EddieO
Later EddieO
No pen used here either. A good cut won't need anything besides a little cleaning the swarf out of the slot, knife works well enough. Occasionally some copper will hang and and the back side of the blade gets it easy.
I know this is old but I was wondering what Tamiya parts tree? Or if there is some other good method for setting up the armature in the Cobra lathe? I am still reading the 90+ pages here. I can't wait to actually try cutting. I need some junk motors to practice. "thumbsup"
EddieO
I wanna be Dave
The shafts are 1/8th, so anything really with that ID and not a huge OD or too tall will work fine. Lots of kits have a plastic washer that works.
Later EddieO
Later EddieO
After Eddie said he was cooler cause he doesn't use anything but his finger with a drop of oil on it (is that right?), I went with that for a while. I'm not in that big of a rush to get things done so I went with what Cobra said to do in their manual. And that is to use a pinion gear to hold the arm in place. Before I set the arm in place I put a washer on, then before I put the pinion gear on, I put a washer there too. It's an arm - washer - cradle block - washer - pinion gear stack. Oiled. Holds everything to the left. Gotta fiddle with it a few times to get as much slop out of the stack, so it spins freely, but has no slop. I've liked that method lately.
Eddie taught me the finger pressure method. I think I burnt a hole in my finger the first time I did it...
It works slick though. I throw a comm washer on the pinion side of the arm and use "light" finger pressure on the comm end to hold the washer up against the lathe block.
Cheers to whoever revived this thread. "thumbsup"
It works slick though. I throw a comm washer on the pinion side of the arm and use "light" finger pressure on the comm end to hold the washer up against the lathe block.
Cheers to whoever revived this thread. "thumbsup"
Oil your finger too, it helps a lot to reduce friction burns. When I chuck 454 Puller arms into a regular 540 lathe I use my finger to keep the arm stable. Just take super light cuts so there isn't much pressure to keep it aligned. On the Cobra I use a few o-rings and washers for shimming, but can't say that it gets used much compared to the Fantom or Taig lathes.
Thanks Holmes!! Yeah I am a newbie so learning curve will be steep! Great advice. I don't know what it is but I have had a fear of lathes..no matter what size since high school. I guess after seeing a friend get hit in the face with a piece of round stock aluminum it freaks me out! I guess when you are a kid you never think about safety and doing things smoothly and properly!! The good news is he had a face shield on and was not hurt but still parts flying and the sounds....yikes!! 
I really can't wait to try this Cobra lathe....i just need some junky motors to practice on. I put an ad in the wanted section
I really can't wait to try this Cobra lathe....i just need some junky motors to practice on. I put an ad in the wanted section
65BAJA
Quarry Creeper
I've been watching ebay for a comm lathe. Is there a brand or model that I should watch out for? Or one that I should avoid?
Hudy and Cobra lathes are good and common, look for the V block Hudy. Xipp lathes can be set up to cut well. Ball bearing supports are cheaper, V block supports are more rigid and resistant to contamination.
Picked up a Cobra Pro Com lathe a few months back. I didnt have a chance to use it till last night and today. I took every motor I had neglected and brought them all back to life. I am no where near as technical or skilled as most of you but I am happy with my finished product. The lathe was set up with a base and dialed in so I did not have to square anything up including the bit. Still need to read up on all of that. The first comm I went at was the worst of the bunch. It took me a few passes to get dialed in on the amount of adjustment and speed in each pass. I have never used equipment like this so I was amazed at the mirror like finish when I was done. Added new brushes and did a break in. I'm glad I invested in this Cobra lathe. Never knew it was so fun. Now just need to get my hands on more motors to play with.
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kurtus
RCC Addict
So after an email to EddieO about the brushes on my Apocolypse 27t type r motor I bought a few years ago he convinced me that I need to cut the comm since I ran through a good 60% of my brushes. I posted here a few years ago about a new integy super lathe 3 that I bought and was all set to cut my comm when it was needed but a few years went by and I never really used the rig much so the lathe never got used. Of course the idiot in me decided I wouldnt need the lathe so I sold it 3 months ago to a buddy go figure. So here we are at the present and guess what I need a damn lathe again lol. I hate asking to borrow things so I set off to ebay and ended up winning a Trinity RC4114 lathe for 21 bucks, is this a good lathe, has me concerned reading binaryterrors post. It is the model that comes with v blocks as well as bearing guides and has maybe made 1 or 2 passes in its life. The seller was awesome and he decided to give me whatever extra arms he had to practice making the cuts before attacking my good brood and holmes motors. I am a little nervous to try my hand at this and to be honest I never used the integy because i never had a arm to practice on. I went onto amazon and found some cheap ar4 carbide bits for 1.79 each so I grabbed 5 to practice with, hope they are not crap. I also decided if I am going to be rebuilding i would grab some motor tools, grabbed a hood alignment tool, brush spring nut tool, brush cutter/serrator, extra 10oz laydown springs, extra 766 brushes and a diamond bit for the cuts on my good arms. All this stuff ran me a total of 110 shipped to my door, now I wait impatently lol.
So with that here are my few questions that I am not totally sure of. EddieO said to run a stock motor on a 3 cell pack, I have a nip axial 27t motor to use and a computer power supply converted with 3.5v, 5v and 12v for power. I also have a special variable circuit to cut voltage down but it is only rated to 3amps so idk if thats usable but it gives me the option to really dial voltage in if need be. I was thinking that the axial 27t on 3.5v would be good but then was told by other sources that 55t on 12v is the best so what is it. I am also not sure where the best place to start the cut is, do I start at the comm tabs side and work to the end and stop, reset back to the tabs and pass again or do you start at the tabs, work to the end and pass back to the tabs as 1 pass? Also is there an easy way to tell if my bit is square since the lathe is used?
hah revived again 1 year later lol.
So with that here are my few questions that I am not totally sure of. EddieO said to run a stock motor on a 3 cell pack, I have a nip axial 27t motor to use and a computer power supply converted with 3.5v, 5v and 12v for power. I also have a special variable circuit to cut voltage down but it is only rated to 3amps so idk if thats usable but it gives me the option to really dial voltage in if need be. I was thinking that the axial 27t on 3.5v would be good but then was told by other sources that 55t on 12v is the best so what is it. I am also not sure where the best place to start the cut is, do I start at the comm tabs side and work to the end and stop, reset back to the tabs and pass again or do you start at the tabs, work to the end and pass back to the tabs as 1 pass? Also is there an easy way to tell if my bit is square since the lathe is used?
hah revived again 1 year later lol.
