Router / Cutter

[justCNCit]

So

Just finished building this but am dismayed to find that the speed of the steppers doesn't even come close to being able to feed the router at the speed it has to go in order not to burn bits right out and the work.

Plus when taking deep cuts at minimum speed the router just stalls out.

Ive considered building a gear/pulley to gear down the speed but this is completely incompatible with this CNC machine.

Does anyone know of a router able to cut at a lower speed with some torque or do I have to upgrade to ballscrews/servos.

If so this CNC can plug itself up the ass after all this work.

[dertsap]

are you close to a princess auto , they have a small variable speed plunge router that has 1/4" and 5/16 collets , its onlt 38 bucks , ive got one for general woodworking and it works ok , or you could look at getting a craftsman

[dertsap]

oops !!


after looking closer at your pic , i guess you do have princess close by

what drivers and motor sizes are you using ?

[justCNCit]

sorry the pictures so fuzzy, the motors are 400 oz in Xylotex with their 4 axis drive box.

Fastest cutting speeds available with this machine is 30 IPM.

[cnczoner]

Perhaps you can get some type of speed controller in there -- depending on the type of motor in your router.

[justCNCit]

It has speed control, its just that it chops the AC current down so that it has little power at the lower RPM's. This has caused it to stall when entering a cut at 30 inches per minute.

I've been told it takes at least 100 inches per minute at the available feedrate in order to reach the right cutting speed. That is impossible without servos on this machine.

Since the steppers work fine at 30 IPM and that speed is fine for me, and many people run machines with steppers and routers, how do they get away with not burning out the work/cutters.

[ger21]

Using 1/2-10 5 start and a hobbyCNC board at 36V, people get 200+ipm with motors similar to those that you have.

[justCNCit]

I will certainly look into that.

[Mike Stevenson]

Originally Posted by justCNCit I don't want to blow my motors

justCNCit,

I think you should listen to ger21. He knows what he's talking about.

[dertsap]

i don t know what kind of resolution you would like but i ran my other system with 3/4-6 acme screws using 400oz motors and it worked great and fairly quick

[justCNCit]

Resolution doesn't much matter so long as it makes the machine work. I've given it some thought over the last few days and figure maybe it has to be done.

Have to source the screws/nuts and the drive board for it though, and at the same time have to work on a tool that tuned in the rails.

[rgoldner]

I believe you are seeing mid band resonance (if you try to tune the motors to higher velocity they don't work well). You need inertial dampers on the motors. Using a Xylotex driver you should be able to double the motor speeds with dampers. A better way to fix the problem is by using Gecko drivers (they are bring out a 4 axis low cost system very soon). Geckos have electronic mid band resonance correction built in.