V-Carve tool marks problem

[jjyoder]

I am somewhat new to the Shopbot but for the most part I have had good success. The problem I've been having with the v-carve is that it doesn't make a clean cut when the depth of cut takes multiple passes to get to the needed depth. It requires quite a bit of sanding to get the marks out. If I'm routing HDU, it isn't a big problem since it sands quite easy.

Has anyone had the same problem that can give me some insight in correcting it?

Thanks,
jjyoder

[bleeth]

Jerry:
The issue can be caused by a variety of things. Knowing your machine model and router type as well as hold down method would help narrow the field.
For example, if you are using a router than the problem may be bit runout but that would not be a problem with a Spindle (I assume good collets in each).
If your parts and/or files are extremely large than it could be the cumulative affect from the amount of tolerance inherent in your machine.
It could be time to replace pinions if you obtained your machine used.

Reply with more info and many here can help diagnose it.

[mitch_prest]

have you checked to see that the bit you are using matched what the bot thinks it has?


m

[jjyoder]

The is a PRSalpha machine that is approx. 1 year old with low hours. This is what I have setup for the 90 degree, 1.25" bit.

5669

[billp]

Jerry,
As other recent posts have suggested it is ALWAYS a good idea to check each, and every router bit to insure it is what the manufacturer claims it is.....
This is also true with "V" bit geometry as many of us have discovered ( after the fact, as in your case) that what we thought was "90" is really 88.3, 89 degrees etc. A good protractor will help here. If the bit IS different than what
your program/machine are expecting you'll get those annoying "watermark"lines you are referring to on occasion...
Check the bit, and if it IS different enter the TRUE angle into your tool library and see what happens then.
Also be sure to check your preview screen, if it looks good in the preview, but NOT in real life, then this is probably an indication of the situation I have suggested above...

[tmerrill]

If your router/spindle isn't exactly vertical to the table, you can get strange results as this will modify the side angle, increasing it on one side, decreasing it on the other. Which side is which depends on what direction your router/spindle is leaning.

Tim

[mitch_prest]

Jerry

take a look that bit is 1 1/4" and that it is 90 degrees.. unless you bought the bit or the previous owner did... then it might not be what you think.. the bot starter set did not include one that size..
just a thought..

mitch

[rcnewcomb]

Here is a handly link on checking V-bit angles: ->Checking V-bit Angles (http://www.vectric.com/forum/viewtopic.php?f=3&t=2164)

[jjyoder]

I guess I was a little naive about the accuracy of these bits. Thanks to all of you for your input. Randall that was a great link. I downloaded the file and ran it. It turns out that my 90 degree bit is actually 89 degrees. With this file it is easy to see where your bit fits in. Again thanks to all of you.

Jerry