bluerustler

I just got my comm lathe and have practised on a old armature so I dont mess up my good one, but Im still looking for some experienced ppl here to answer some ?'s. When cutting into the comm, should it cut really easy like butter or is it spose to a little bit a pressure? I have the Team Cobra Pro com, and on the depth wheel it has the lil lines about maybe 2 mm space apart, when increasing the cutting depth, do I wanna go to the next line or increase half way in between or what? Also, I used my normal 7.2 batter pack, I know most ppl use 4 cell packs but i dont have on and and I tried using a 5 volt dc power supply and that wouldnt turn it as soon as I started to cut. But anyways when I used my battery I used up all the juice cutting just the 1 comm, is that normal or should the battery last longer. And help would be great, any other tips would be awesome too.

Thanks guys!

Speedmunkey

It should be butter. Any resistance that could stop the arm, can also destroy it and your bit. Take multiple very light passes instead on one large one. Takes longer, but then precision usually does. Don't forget comm cutting fluid and to lube the shaft were it spins in the blocks.

bluerustler

I read I could use bearing oil which I did is that ok? And should I re-oil the comm after each pass or is the 1 time at the beginging ok? And how about using the battery? Thanks for the help so far.

Speedmunkey

I put it on every time I make a pass. But, oil too much probably cuz I figure too much will just fling off, while not enough will cause problems. Oil is cheap compared to a motor. Bearing oil should work, but comm fluid is the same price so get some when ya can.

Can't help ya on the battery thing. I use a 12v power supply with mine,

bluerustler

do you use a actual 12 V power supply or a PC power supply, I tried using a PC one like I use to run my battery chargers but I ran it off the 5 volt wires. It didnt seem to work really well though, not enough power to turn the motor is what it seemed like but I dunno. But if you do run off of 12 volts, wouldnt that go even faster than a 7.2 volt battery? Or is there a diffrence some how.

scale only 4 me

My Feedback: (158)

Do yourself a favor and make up a 4-cell pack for the lathe
You gotta have some old battery packs laying around

the 5volts you tried most likely didn't have enough amps

bluerustler

I wanna make a 4 cell pack, but then Im not sure how I will charge it, my chargers are for 6,7 and 8 cell packs. would they work ok to charge a 4 cell as long as I maybe timed them and shut them off before the full charge?

Mike Ledbetter

You know, a receiver battery pack is 4.8 volts (nominally) and will charge with the wall charger that came with the pack. I haven't used one yet, but when my comm lathe is delivered, I plan on trying to power it with one of these packs to start out with.[&:]

Maybe you could try it first and tell me if it works

Speedmunkey

I run my lathe, the Integy Auto Super Lathe, off a 12v switching power supply, also sold by Integy. The Auto Lathe has a built in motor control. It isn't direct wired. I'm sure there is stepping down of the power.

bluerustler

well, I rigged up a 4 cell pack but havnt really used it yet. But today I was thinkin, can't I just use my speed control from my car? just unhook from the car motor to the lathe motor, then just turn the throttle trim to an ok looking speed? Or is there a risk of wrecking something that way.

Mike Ledbetter

I've been wondering the same thing. ESCs are discouraged for motor breakin because the power is delivered in pulses, not continuously like DC from a battery.

But why would that make a difference in spinning an armature with a rubber O-ring as a motor belt? I think the speed of the spinning armature would be constant, or so close as not to matter during the pass with the cutting bit.

Even if there is a difference in using an ESC, what about this mechanical speed control I have left over from a Tamiya kit? That seems like an MSC would provide a mechanical step down at a constant voltage.

Any thoughts on this?

bluerustler

Well, I used my ESC to power with, was a little short on power when making the cuts but it worked. Now what I wanna know is. How do you know when the carbide cutting bit is dull or done with. Its only one end of the bit you can use to cut, right. If the used lathe I got wasnt all assembled with the bit in place, I prolly woulndt even know which end was used for cutting. Is it possible to cut with a dull bit or will it just rip everything up on the comm? My cuts arnt the best yet but I think thats because I dont know everything I'm doing yet, but they they made my motor run better.

Mike Ledbetter

I'd like to know the answer too. I would guess you replace the bit when it won't cut as well, but I got mine new.

I tried the mechanical speed control, but the lowest setting was still pretty fast. I have been using a 4.8 v (4 cel) 600mah receiver pack and it works fine, at least for two comms worth of cutting.

I am making a 4 cel pack from 3000mah sub-c cells to use in case I want to cut comms for others. Do folks at the track charge to cut their fellow racers comms for them?

Speedmunkey

That boys, is a question for Big Jim.. www.rccars.com He has a thread for just about every subject relating to rebuilding/tuning motors.

I don't normally promote other forums on a board, I think it is rude. But this is where Big Jim (one of the giants in motor information) makes hs home. You just can't get his knowledge on this board. Sorry RCU.

As for charging, that depends on who is it. A friend? Nope, I'll do it for free... Someone I don't know? They'd pay a minimal fee for my time, like $5. So far I've only cut for friends though.

Hey Mike, how's that Trinity lathe treating you?

Mike Ledbetter

Munkspeedy,

I practiced up on a junk non-rebuildable motor. I have cut two different Speed Gems motors (once each) on this truly superior Trinity product, and they run both run great and much quieter. I look forward to cutting many more, enjoying the gratifying benefits of the non-automatic, infinitely adjustable speed at which I can pass the cutting bit over the comm. [&:]

This is the link to the Tower page:

http://www2.towerhobbies.com/cgi-bin...?&I=LXWS76&P=7

and I will attach the image so you can see the lathe itself. It looks to be of really high quality aluminum. I put a stock 550 (from a Tamiya kit) into it and power it with a four cell receiver pack, until I get my four cell subC 3000mah pack built.

Regards to all.

Speedmunkey

Glad yer liking it, but I too can pass the bit over my comm at will. Just cuz the name implies "automatic", does not mean it has no manual mode. It has a rocker switch, for forward and reverse at whatever speed you choose. What I like is that the speed it passes is always consistent, however ya wanna set it. I had no motor to install, as mine comes with a motor designed specifically for this task.

Make mine Integy thanks

bluerustler

Do they make bits with Cobalt ever cus on the bottom of my bit it says Mo-Max COBALT. If it is, is it weaker than carbide bits, can I sharpen it back up like you can with carbide?

Mike Ledbetter

Speaking of Big Jim,

His Black book of Motor Secrets (or whatever it's called) is on the sale table at Border's right now for 75% off which equals $5 for this book full of knowledge and info on the design, tuning and maintenance of RC motors. I got one by surprise; if there's a Border's near you and you read books, this could be your lucky day.

Regards.