Desk top Shopbot

[Haitham]

Hi
I am new to the cnc world, I've purchased a desktop 2 months ago for my hobby, and I've been experimenting with it. I have three issues:
1- I am doing some engraving on a piece of Corian, since its surface is uneven the engraving has different depths at different areas, would you recommend a spring loaded tool for the problem? And is it compatable with the desktop?
2- I left the machine engraving a 6 hr job at depth of a fraction of an inch, when I came back after it finished the job, I noticed that it went crazy at some point and plunged all the way to the bottom of the piece engraving a small area the full depth. Does anybody have any suggestion as what might have happened?
3- While doing a table surfacing job the tool was plunging deeper as it cut the interior area making it different levels, lookin like a seating in a stadium.
After this job the tool would not go up. It would go down no matter what I press on the console. Any idea?

[myxpykalix]

1- I am doing some engraving on a piece of Corian, since its surface is uneven the engraving has different depths at different areas, would you recommend a spring loaded tool for the problem? And is it compatable with the desktop?

My experience is with flat corian. However if you are using an uneven material then you need to go back into whatever program you use and remake the file so that you use the "table" as your Z zero point. And then give your engraving aa specific depth.

Then when you mount your material you set your Z zero to the surface of the table. The result will be that the machine will cut your engraving to a specific depth based on the height of the bit from the surface of the table.
The problem you have now is that you are probably setting your Z to the highest point on the surface and when it gets to a dip in the material it doesn't cut as deep thereby causing the uneven depths.

2- I left the machine engraving a 6 hr job at depth of a fraction of an inch, when I came back after it finished the job, I noticed that it went crazy at some point and plunged all the way to the bottom of the piece engraving a small area the full depth. Does anybody have any suggestion as what might have happened?

You might want to post a picture of the results or your file for others to look at and maybe analyze your settings, or nodes or any number of other issues.

3- While doing a table surfacing job the tool was plunging deeper as it cut the interior area making it different levels, lookin like a seating in a stadium.
After this job the tool would not go up. It would go down no matter what I press on the console. Any idea?

Again, a picture is worth a thousand words, but this sounds like it might be an issue for Shopbot tech support.

[jerry_stanek]

It could be that the z is binding up and losing steps when it goes up or a slipping grub screw on the gear.

[Haitham]

Thanks to Jack and to Jerry,
Actually my Corian is also flat but it is not 100% due to manufacturer defect, and if you notice from my pictures my engraving is very fine and covers the whole area.
I have attached pictures of both the surfacing job (red) and the engraving job(black)

[ccciw]

The stair step problem that you are experiencing may be caused by a loose tool. It appears to be pulling down as your program progresses and spiral fluted cutters can pull themselves completely out of the collet if not tightened properly.
I would also suggest that you decrease your tool step over, try using ½ to ¾ of the cutter diameter for this value. Surfacing will take longer but you will eliminate the ridges that can be caused by using the full cutter diameter for the step over value.

Hope this helps,

P. Camp

[jerry_stanek]

It looks like you need to align the router to the table top. If it is not straight up and down both front to back and side to side you will get those ridges. I st ill think something is binding up or pinion gear is slipping.

[zeykr]

Do you have a router or spindle? If spindle, are you properly snapping collet into nut before putting it in the spindle? The table surfacing looks to me like you may not have the spindle/router plumb, though hard to tell from the picture for sure.

There may be several little problems here, but they can be worked through. Is it possible to post your partworks file, or tell us the speeds, feeds, bit used etc and maybe someone can be of help.

[myxpykalix]

It also looks to me like you have some issues with your file. You may have too many nodes in some parts where it cut thru. Because it cut thru within the borders of that design suggests to me that it is an issue with the file rather then a mechanical issue that would present itself all over within the design.

But what do I know...i've been wrong before!:eek::confused:

post your file for others to examine.

[Haitham]

Guys I am overwhelmed, thanks a lot for all your help. I have tried to attach the sbp file but it would not upload as it is about 4 mb. Meanwhile, I will be trying your solutions once I have a chance. I will get back to you then.