Messages

101

General Mach Discussion / Re: changing out bits but keeping bit length...

« on: January 26, 2010, 01:32:38 AM »

Kind of ghetto, but I sanded down a bit holder tube so I can but it on the bit and push it into the collect, and it'll rest on the surface of the collet at 35mm length for the bit.  I tested it with several different bits and they all end up being 35mm, or very close to it.  Is that the kind of thing people do to change things out?  I think I should probably machine a real tube/holder for this using aluminum, but this was damn easy to do as a test.

Barry

102

General Mach Discussion / Re: A Really Exceptional Vendor....

« on: January 26, 2010, 01:27:54 AM »

I've ordered from Keling a couple times, no issues.  In fact all the vendors I've used were really good for my machine, except HSD.

The good are, Home Shop CNC, Keling, 80/20, Gopher Electronics, McMaster Carr, CNC4PC, Doughty Drive, Gecko Drive, Automation 4 Less, all good.  I've gone back to them time and time again and recommend them highly.

Bad is HSD.  In fact, I hope nobody orders from them again;)

103

Show"N"Tell ( What you have made with your CNC machine.) / Re: rough cut prob

« on: January 26, 2010, 12:18:03 AM »

No need to get testy.  I think by your own definition this is probably not flex since your plywood/mdf machine has a fair bit of visible flex.  This is a extruded aluminum and aluminum plate router.  The flex is nearly nonexistent.  I could probably stand on the gantry if I wanted it and it wouldn't flex visibly.  The only flex, I can discern is from the B/C head and even then it's so incredibly small.  I'd have to pull on it, with I bet about 70 lbs force.

I took the part and jig pieces off the table.  Remember I said the bit went through the plastic jig and basically melted it?  Well, I'm willing to be that's the reason the bit was biting.  Look at this:





I bet that melted plastic basically acted like glue and the bit never recovered from it.

And, btw, these jigs aren't really meant to secure a part to a table.  I need to make some that do.  They were the closest thing I could find at the hardware store;)

Still though, I'm going to try out everybody's suggestions.  For the next test, I'm going to use a 3mm stepover, 5mm depth, 160mm feed rate, upturn bit, and 14,000 rpm.  Wish me luck.

Barry

104

Show"N"Tell ( What you have made with your CNC machine.) / Re: rough cut prob

« on: January 25, 2010, 06:41:20 PM »

As I stated before, that only play I see right now is from the B/C head itself.  I suppose that could cause the issues, but that's not something in my control to fix as it's 3rd party.  I have to investigate the other avenues first.

15000 mm/min, that's just crazy to me.  He must have a very high hp machine, mines only 2 hp on a gantry with the b/c head.  There's no way I could move mine that fast.

Barry

105

General Mach Discussion / Re: changing out bits but keeping bit length...

« on: January 25, 2010, 03:46:36 PM »

Interesting idea, thanks!

106

General Mach Discussion / Re: changing out bits but keeping bit length...

« on: January 25, 2010, 03:10:20 PM »

As this machine is 5 axis, I can't really just zero the Z again, it's gotta be the same.  However, I can do the multiple collet's and set up tools.  For this though, can't the bit slide in the collet till you tighten it onto the machine?  How is that locked into place?

Also, do you need two collets, and two collet nuts?  Or can you slip one collet out an the other in, without disrupting the spacing.

Barry

107

General Mach Discussion / changing out bits but keeping bit length...

« on: January 25, 2010, 12:56:41 PM »

Hey folks, I'd like to do a rough pass with a larger bit, and a finishing pass with a smaller one.  To do this, I need to switch out the bits mid job.  I'm sure this is a newbie question, but I'm a little dumbfounded.  How do I ensure that I have the same length of the bit for the finishing pass.  That way I can switch it out and continue immediately.

Barry

108

Show"N"Tell ( What you have made with your CNC machine.) / Re: rough cut prob

« on: January 25, 2010, 10:20:54 AM »

The only flex I have in the machine is from the B/C drive itself.  The rest is really really sturdy.  I'll try using an upward spiral, and a shallower depth.  I think the 5mm, stepover might be a bit much too.  I'll make it the radius of the bit instead.  I did notice one thing after looking at the bit.  The plastic clamps I was using were cut into with the bit and I think it acted like glue to the bit.  I think that's one of the reasons the bit was biting.  Hopefully I'll have more to show very soon.

Barry

109

Show"N"Tell ( What you have made with your CNC machine.) / rough cut prob

« on: January 24, 2010, 07:55:28 PM »

hey folks, I've finally got my issues with the smoothstepper and mach in order and am now doing a big rough cut.  I'm running into an issue where the bit is starting to bite into the wood instead of smoothly cutting.  I little roughness is fine, since this is a rough cut, but it was really biting.  I caught it a bit too late as the bit broke;(



This is happening about 3/4 the way through the rough cut.  The beginning was fine.  The depth I'm doing is 9mm, so not too bad and 90mm/min feed, nothing crazy.  The bit is double fluted 6.35 mm, downward spiral.  My overlap is 5mm for the roughing.  The spindle is spinning, approx 14,000 rpm.  Is this an indication of the bit wearing out?  Or should my feed rate be slow, or should the spindle be spinning faster?  Maybe the depth is too large?  Is my overlap too large?  Should I use upward spiral instead?  I don't think the feed rate is too slow, as it's almost intolerably slow;)  I was thinking of increasing the feed rate till I saw this happening.  I'm new to this, so this like most issues is an all new problem to me.  So you people that are more used to issues, please let me know what you think.

Barry

110

Show"N"Tell ( What you have made with your CNC machine.) / Re: Routed Teak Tiger.

« on: January 21, 2010, 10:53:05 AM »

hee hee, love it.  You guys are all doing great work!

Barry