Possible Controller and/or Mechanical Issues with an HD3

[Viper500]

I have a Shark HD3-I bought it from Rockler-and am experiencing a couple of problems. Got it in December or January. It has the 2.1 control panel. I am new to CNCs and needed a project so I decided to do a cribbage board. It is 5.5" x 20". I oriented the project so that the 20" was left to right. I dumbed it down so it only uses two tool paths. I am using VCarve Desktop 8. The text and lines were done with a 60 degree V bit using a V carve toolpath and the holes were done with an 1/8" end mill and a drill toolpath. I am on version 10 or more due to issues I have found along the way with my design. It is one of those things that look good on the screen but it couldn't be built. I have those issues resolved and am now trying to make the final product.

Problem #1.
Everything seemed to be working but then I noticed that the drilled holes were elliptical and not round like they should be. They are 0.125" in the X plane but 0.144" in the Y plane. I reviewed the G code and there doesn't seem to be anything wrong with it. Rockler has a CNC club and I presented this issue to the members and they suggested that there might be some mechanical play in the Y axis, but I can't find any. All the holes are identical. I don't seem to be having a problem with the text or the lines.

Problem #2
The project requires two tool paths: a V Carve and a drill. I have been doing the V Carve first and then load in the drill toolpath. Twice now, as soon as the new drill code starts loading the gantry goes to the upper right corner of the bed and crashes. I have to hit the E Stop power button on my system.

Could I have a defective controller? Could these two issues be related? Any ideas?

Thanks.

Mike Timmerman

[rungemach]

Hello Mike,

Regarding the oval shaped holes, some of the "usual suspects" would be free play, or gantry alignment.

You may want to check to see that you don't have free play in the y direction. If you do, it could be traced to the linear bearings or loose bolts etc.

The gantry alignment issue can show up quite visibly with small holes. To be in alignment, both the bit itself and the entire z axis needs to be perpendicular to the work plane. If only the bit itself is at 90 degrees to the work surface but the axis travel is not, you get oval holes that get more oval (at the top of the workpiece) as the hole gets deeper. To align the machine properly , the axis travel must be perfect as well as the alignment of the router to the axis.
That way the bit is perpendicular to the work and is moving down into the work following a perpendicular travel path.

Hope this helps.

Bob

[sharkcutup]

Could be z-axis play - on my shark I noticed on the downward plunge the z-axis lifted towards the y-axis. You may want to check the bolts for tightness on the z-axis too. Also look at this post http://www.cncsharktalk.com/viewtopic.php?f=9&t=5020 it may be worthwhile doing when you check the z-axis.

Have GREAT DAY!!!

Be SAFE around those AWESOME machines!!!

[bill z]

Viper,

Another thing to check is that your router is exactly perpendicular to your cutting surface. If it is off a degree or to, the hole you cut or drill will be at an angle on a plunge may cause an oval.

There are a few posts on this forum that will help you check and shim your router.

Here is just one. http://www.cncsharktalk.com/viewtopic.php

[Rando]

The other thing to keep in mind is that the plunge rate cannot be so fast that it deflects the plastic head. If you watch carefully as the bit plunges, you can see how the whole z-axis flexes during that push downward. That definitely can lead to out-of-round holes. I generally do quite slow plunges, in the 4-10 IPM range, and I even put a G04 dwell command at the bottom of each plunge so it at least has time to get to the intended bottom. That required a post-processor change, so not for the faint of heart .


Thom