Accuracy with small end mills

[GuitarEng]

Howdy,

I have been using my k2 to do inlay in various types of wood using mother of pearl, turquoise, and other woods. I've had some problems obtaining good accuracy with small end mills using the DA300 assembly to hold my 1/8" shank bits. I use bits down to about .020" in diameter for some of the more detailed stuff.

The spindle on my machine is a porter cable router...using the standard 1/2" and 1/4" collets I can cut to within about +/-.001. However, I'm about .005" out at the end of the tool using the DA300...it frustrated the heck out of me for awhile and I thought that my CAM package was generating bad code on these small patterns. I've since wised up and found out that excessive runout on this DA300 was the problem.

I can work around this now that I know how much it runs out...but I'd much rather program one to one. Does anyone know where we could get 1/8" collets for the Porter Cable routers? Alternatively, if anyone knows where to get mini mills with a 1/4" shank I'd love to hear it!

[Blaine]

GuitarEng,

Probably the easiest thing to do is to use a sleeve adapter. These add overall tool length, could be good or bad, this depends on your application.

Do a search, there are many available online.

Good luck,

Blaine

http://productivecnc.com/

[sploo]

I ordered a set of adaptor bushings from http://www.mlcswoodworking.com. It was product code #300, but I can't find it on their site at the moment, so it may not be available now.

[hindocarina]

I've got the same setup as you, and I use ER-11 collets. I haven't measured the runout, but they are more accurate than the DA. Here's a link to a holder:

http://www.use-enco.com/CGI/INSRIT?P...PMAKA=308-0018

[hindocarina]

GuitarEng,

I haven't cut anything as small as you are talking about, but since I'm interested in it and am also using a 3925 with the Porter Cable router, I decided to do some runout measurements. The results are disappointing.

First I measured the internal taper of the spindle itself. Runout=.0017".
Then I put a 1/4" bit in 1/4" collet and measured the runout on the shaft 1/8" from the end of the collet. Runout=.0043"
Next I put in the 1/2" collet and measured a 1/2" shaft the same way. Runout=.0048"
Finally I put the ER11 collet chuck into the 1/2" router collet and measured a 1/8" bit 1/8" from the end of the chuck. Runout=.0084"

I guess if I ever start cutting anything that small, I'll tell ArtCam that my cutter is bigger than it really is to account for the runout. Shouldn't this compensate without any additional problems?

Charlie

[9lrac9]

Rutland Tool has 1/4 shank end mills to small Dia, in ther weekly catalog cheep
and portercable does not make a 1/8 collet, as I asked if they would make me a 5/16 collet. And don't forget it is still a router your dealing with... If your router has only .001 runout I want your motor, I have a new 2 1/4 hp on my K2 14x14 and with a 1/4 tool 1.00 long I have .004 run out. Heaven knows what my 3/8 x 1.750 over all cutting lenght is running out. If your making your system work doing inlays with what ever tools your using, try all your speeds and feeds to get the best, if you feel you need to spend another 80.00 to 100.00 to gain a few thousands in accuracy, is it worth it?

9lrac9 Happy K2 CNC owner
PS I have two router motors 1 3/4 and 2 1/4 and 1 3/4 for the accurate stuff...

[njitnjau]

Hi
I´ve been runing a K2 kg3925 with a porter cable for a while.
I found that I got various sizes of my cuts every time.. I started to measure the router bits with a dial indicator and found that it sometimes was up to 2 tens of a millimiter of center. this means i get a cut that is 4 tens of a millimeter too wide.. Anyhow, I tried to rotate the collet and bit within the collet nut, like one eight of a turn, then measure again, turn measure until I got the bit to sit in center.. It works! but its a tedious work every time you change bit.

I got so frustrated so I bought a HSD 2,2hp spindle and a new custom 8"travel Z axis.. problem solved!!!
K2 made a Z axis with the servo mounted upside down for me this way I get a more compact Z axis.
And to have all Z movement I was used to with the porter cable and a 5" travel Z, I found out that it was neccessary to have 8" travel with the HSD since you cannot slide the spindle up and down in the mount.

/ J

[hindocarina]

Sounds like a good solution. What all was involved with installing the new spindle? How much did the new rig set you back? I'd like to see some pictures of the new setup too.

Thanks,

Charlie