TEDROCKZ
I wanna be Dave
You finally put out for a camera
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Some of those tools are basically extinct.
. Some of those tools are basically extinct.
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Cutting a motor commutator & motor tweaks
- Thread starter EeePee
- Start date
It's cool shit! I'm gonna take some more pictures of how it works, later.
EddieO
I wanna be Dave
All the stuff is on the site, except the fussy brush.....I dunno fully what I have left of them. Some of its not cheap....but the prices on most are actually cheaper than they used to be......Tedrockz is right, most of this stuff is the last of it in the world and will never be made again....the Sonic Fiddlestick being the only one still in production (there is a diagram on the site of how it's used)
EeePee might not of noticed the other use of the timing jig, though his pic shows it a little. You flip the unit over, the 4 holes are designed to be used as a shock rebuilding station.
Later EddieO
EeePee might not of noticed the other use of the timing jig, though his pic shows it a little. You flip the unit over, the 4 holes are designed to be used as a shock rebuilding station.
Later EddieO
Anyone have any advice on setting up a motor lathe? I'm borrowing a Integy XIPP and the bit it came with was cutting horribly. I did some research and came across this article that seemed helpful: http://www.hobbytalk.com/bbs1/archive/index.php/t-127008.html
I noticed the bit had a large stack of shims under it placing the tip way high over the comm. I ordered two of the McMaster bits cited in the article, re-shimmed according to the directions and it still cuts awful. Very loud, rough surface kinda nasty. Not sure what motor is on the lathe but it seems pretty fast. I only have 2s lipos to run it off of, but the last time I borrowed one of these, the owner said it cut better on 3s (it did), despite the instructions saying low voltage is better. Before I ruin this arm ( if I haven't already) what am I missing?
I noticed the bit had a large stack of shims under it placing the tip way high over the comm. I ordered two of the McMaster bits cited in the article, re-shimmed according to the directions and it still cuts awful. Very loud, rough surface kinda nasty. Not sure what motor is on the lathe but it seems pretty fast. I only have 2s lipos to run it off of, but the last time I borrowed one of these, the owner said it cut better on 3s (it did), despite the instructions saying low voltage is better. Before I ruin this arm ( if I haven't already) what am I missing?
EddieO
I wanna be Dave
You have it spinning WAY too fast......even with a lathe motor, 5v is probably the threshold to be spinning off it.......I cut at 2.5 with my fantom (mine has a custom armature in it).......most lathes around 3v is good.
There are TONS of old nimh chargers that can run a motor, most of which you can get for next to nothing.
Worst comes to worse, just make a small NIMH pack(3 cells).....even two akaline batteries would be better.
I am guessing at this point you have it spinning WAY too fast, along with the blocks may be misaligned.
Later EddieO
There are TONS of old nimh chargers that can run a motor, most of which you can get for next to nothing.
Worst comes to worse, just make a small NIMH pack(3 cells).....even two akaline batteries would be better.
I am guessing at this point you have it spinning WAY too fast, along with the blocks may be misaligned.
Later EddieO
Maybe spinning the arm the wrong way? I did that for a second and it chattered.
Man, 2S lipo voltage... with what motor? If it's a 55 turn it could be okay? Wasn't it intended to use a 55 turn on a 12 volt tap?
I use a freshly peaked 3 cell NiMH GP3300 pack, with a 27 turn stock motor, and I've always thought that was a tad fast. It throws copper about a foot away on the countertop, I got a nice pile going. :ror:
Man, 2S lipo voltage... with what motor? If it's a 55 turn it could be okay? Wasn't it intended to use a 55 turn on a 12 volt tap?
I use a freshly peaked 3 cell NiMH GP3300 pack, with a 27 turn stock motor, and I've always thought that was a tad fast. It throws copper about a foot away on the countertop, I got a nice pile going. :ror:
Alright, I took the motor off the lathe and it appears to be a 27t:shock: So I put in a 70t (my only option) and tried again on 2s. Much slower, but still awful. The top of the arm I am trying to cut spins away from me, which is how it was wired originally. I think this thing has just been screwed up by the PO. The other one I borrowed ran a 45t on 3s and cut perfect.
I don't have much experience setting the things up, so I really can't help.
Yeah top of the arm spinning away from you, bit not too high above the centerline, and not cutting cones is about all I know. And direction of bit angle relative to direction of cut...
Yeah top of the arm spinning away from you, bit not too high above the centerline, and not cutting cones is about all I know. And direction of bit angle relative to direction of cut...
killswitch
RCC Addict
Thats the basics that every comm lathe Ive ever used needed.
Ive never ran near that kind of voltage at a comm lathe before... max Ive ever cut at was 4.8v (old 1/12 scale racing pack). Im with Eddie... I cut at around 3v with a 27t arm (if i'm not mistaken). You want the bit just a hair above the centerline of the comm. I'm thinking maybe the bit is in incorrectly. Pics would be handy to diagnos your issues...
EddieO
I wanna be Dave
THere is some great lathe threads on hobbytalk, but better ones on the rccars.com........the search engine works like shit, so just scroll back to like 2005 when Big JIm died.......he had his own forum, but I think its just the motors and batteries forum now.
Later EddieO
Later EddieO
The bit should contact on the same level as the center of the comm, you can get away with a hint above center. With copper you do not want much rake, but you can have plenty of clearance. I prefer to spin very fast, and take very light cuts. on my mini lathe I use a 55t motor on 3s. This way you can get away with a sharp HSS bit and get beautiful finishes, although carbide or diamond is nice because you don't have to sharpen them often and they will cut deeper with less chatter.
Typically I start with 10 degrees of relief (clearance between bit and comm) and 25 degrees of rake (from parallel line to line 1). Copper is grabby, so you cant have too much rake or too narrow of a wedge. Learning to grind your own tools is a start http://www.nzdl.org/gsdlmod?e=d-000...a=d&cl=CL2.4&d=HASH018ca5ce4989eb53055a263a.4
Typically I start with 10 degrees of relief (clearance between bit and comm) and 25 degrees of rake (from parallel line to line 1). Copper is grabby, so you cant have too much rake or too narrow of a wedge. Learning to grind your own tools is a start http://www.nzdl.org/gsdlmod?e=d-000...a=d&cl=CL2.4&d=HASH018ca5ce4989eb53055a263a.4
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I would have posted such info earlier in the thread, but I wanted to get more time cutting different materials before putting in my two cents. Right now I am dealing with how to face PVC with a smooth finish, that stuff is hard to cut without melting!
EddieO
I wanna be Dave
Spinning WAY too fast.....
Big Jim, Mike Reedy, Jim Dieter, Troy Schroeder, Eric Anderson, Todd Putnam, Chad Phillips, Oscar Jansen.........all used sub 5 volts with a lathe motor (usually 45t or more).....mine are custom 65t, balanced to stupid perfection....
But what would all of us know....."thumbsup"
Must be fun when an arm spins off the lathe at 11k RPM......
Later EddieO
Big Jim, Mike Reedy, Jim Dieter, Troy Schroeder, Eric Anderson, Todd Putnam, Chad Phillips, Oscar Jansen.........all used sub 5 volts with a lathe motor (usually 45t or more).....mine are custom 65t, balanced to stupid perfection....
But what would all of us know....."thumbsup"
Must be fun when an arm spins off the lathe at 11k RPM......
Later EddieO
Probably bit placement. If the comm is turning away from you at the top, your bit will have to face downwards for the cut. Maybe the comm is just rotating the wrong direction, but doing that will have ruined your bit too.
Pics will help for sure.
Soft copper machining is generally around 200 feet per minute face speed, taking "normal" cuts. There isn't just one way to do it, and there are ways to get fine finishes with slow face speeds "thumbsup" As an example, a 10mm diameter comm converts to .39 inches roughly. Multiply times Pi and we get 1.2246" circumference. That is close enough to .1 foot, so we can turn the 10mm comm at 2000rpm for starters. Light cuts can be made at faster speeds, and sharper bits (diamond, carbide) allow for slower face speeds and deeper cuts.
I use HSS bits. My mini lathe has roughly a 3 to 1 geardown, as does the Xipp lathe with the proper pulley. Turning the 55t on 3s gets around 9k loaded. This gives me an arm speed of 3000 and face speed around 300fpm, but I take very light cuts around .0001" at a time. Using a diamond bit I could get away with half as much speed and get the same finish. If I wanted to take .0002 or .0003" cuts with the HSS bit I would slow it down further as well. However, I have found that copper is so much easier to cut fast and light than slow and heavy. When taking heavier cuts with HSS there is a tendency for the copper to grab and pile up between the comm segments, and that is just a huge pain.
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Ok, got some pics.
Lathe as set up by PO, minus the huge shim stack and with the 70t motor.
Bit placement.
The mauled comm.
New bits right vs. old on left. New ones are carbide AL4 as suggested in the article. They look different on the tips, almost rounded, is this normal?
New bit mounted (correctly?)
Hope someone can make sense of this.
Thanks
Destroyer
Lathe as set up by PO, minus the huge shim stack and with the 70t motor.
Bit placement.
The mauled comm.
New bits right vs. old on left. New ones are carbide AL4 as suggested in the article. They look different on the tips, almost rounded, is this normal?
New bit mounted (correctly?)
Hope someone can make sense of this.
Thanks
Destroyer
Rounded tips are fine if they are still sharp.
Looks like that bit needs to be lowered down a lot. You are just rubbing the bit on there right now. The cutting edge should be even or a hair below parallel with the shaft center with the way you are cutting.
Can you flip your bit mount 180 degrees and flop the arm around the other way? With the way it is set up, you can't get the bit low enough.
Looks like that bit needs to be lowered down a lot. You are just rubbing the bit on there right now. The cutting edge should be even or a hair below parallel with the shaft center with the way you are cutting.
Can you flip your bit mount 180 degrees and flop the arm around the other way? With the way it is set up, you can't get the bit low enough.
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