Suddenly, I'm not getting accurate routes

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PapaBear60
Posts: 8
Joined: Wed Sep 22, 2010 4:11 pm

Suddenly, I'm not getting accurate routes

Post by PapaBear60 »

I've had my Shark for more than a year and love it - until today. I was routing some very simple work, pockets comprised of a rectangle with rounded ends, created by joining two circles to the rectangle shape. These are 2 3/4" long and 1/2" wide. I'm using a 1/4" end-mill, and creating several of them adjacent to one another at a slight angle (13 degrees). I noticed right away that they appeared to be somewhat less than 1/2" across ... so, out came the old calipers and sure enough, they were nearly 1/16" too narrow. That's never happened to me before, it's always been dead-on. The only solution I could think of was to lie to the software about the size of the end-mill, ultimately telling it that it was .23" rather than .25, so it had to move the tool out appropriately to assure the hole was 1/2".

Anyone got any ideas?

spinningwood
Posts: 191
Joined: Wed Aug 04, 2010 11:28 am

Re: Suddenly, I'm not getting accurate routes

Post by spinningwood »

While you have the calipers out, check the diameter of your tool (both shank and cutting edge). It's possible that the cutter your are using is undersize. A couple thousandths is common.

You could also open the toolpath file in either notepad or the control panel and scroll down through the code (it's plain text) and see if the instructions call for the tool to move enough to cut the full 1/2". (coordinates would be offset by tool size). This would help you narrow down whether it's an issue with the shark or if it's something you are doing with a setting in the software.

Whatever operation you are using (profile or pocket), make sure you didn't accidentally set any allowances.

If you don't see any obvious problems, then if you post the *.crv and *.tap file I would be willing to look at them to see if I can spot a problem.

My guess is that it is probably not the shark, but I'm just guessing.

Ed

Tim Owens
Posts: 361
Joined: Wed Jul 28, 2010 3:51 pm

Re: Suddenly, I'm not getting accurate routes

Post by Tim Owens »

is this dead on in one axis and off in the other? This could be a loose coupler issue from the motor to the drive shaft.

PapaBear60
Posts: 8
Joined: Wed Sep 22, 2010 4:11 pm

Re: Suddenly, I'm not getting accurate routes

Post by PapaBear60 »

OK. First, Tim I did check the connectors and all seem secure. The error appears to be both x and y, as can be seen in the files which I would attach but it won't take a zip file

As for the setups, I've attached a bunch of files, and they are described here:

1. Project... :: This a picture of the original project, creating stiles for a set of fixed louver doors. The MBR Panel.crv and 11 Pockets.tap are the files producing the holes in the original project. I'm using a 1/4" end mill (two different tools).
2. EndMill_Diameter... :: this is a picture of the caliper reading on the end mill. Note that it is .002 - .003 smaller than 1/4", but that could also be the fact that I don't have the calipers exactly on the blades (2-blade and up spiral seem to have same results).
3. Target Application... :: this is a picture of two of the pockets that I need to route for this project. They should be 1/2" by 2 3/4", and appear to be off in both directions.
4. Test Route... :: Because the application has the pockets on a diagonal, I reordered it and removed the curved ends to simplify reading the (Test Panel.crv is four pockets, the first two are the two diagonal pockets, the next is the rectangular, and the last on is the elongated oval pocket, rotated to vertical for easier read. The TAP produced is Pocket 1.tap).
5. Test Route.jpg :: this is a picture of the rectangle that I'm measured (all seem to have the same result, BTW). The following files relate to this test:
5a. Test Route Setup 01.jpg :: picture of the rectangle and its seetup
5b. EndMill Setup Table.jpg :: picture of the setup table
5c. Caliper for Width of Test and Caliper for Length - pictures of the caliper reading showing the both the length and width seem to be off by 1/32".

I am open to any thoughts ... thanks in advance.
Attachments
Shark1.zip
First of 2 files, apparently it will only take one file less than 256K.
(219.94 KiB) Downloaded 442 times

PapaBear60
Posts: 8
Joined: Wed Sep 22, 2010 4:11 pm

Re: Suddenly, I'm not getting accurate routes 2nd ZIP file

Post by PapaBear60 »

This is the second ZIP file for the previous reply with the looooooong explanation.
Attachments
Shark2.zip
(140.98 KiB) Downloaded 441 times

spinningwood
Posts: 191
Joined: Wed Aug 04, 2010 11:28 am

Re: Suddenly, I'm not getting accurate routes

Post by spinningwood »

I checked all your files and ran the Pocket1 Toolpath on my machine.

Here's a couple things to try / check:

1: When defining the toolpath for something like this use "offset" instead of "raster" in the "clear pocket section". I ran the Pocket1.tap that you calculated using the raster setting with an end mill that I know is 0.249". The slot produced was 0.48". I recalculated the toolpath (using offset and conventional) and ran it again. This time he slot was 0.494". It makes a difference. Not bad, but not perfect.

2: If you are doing things with the shark that are dimensionally critical (like making parts that have to fit together) you must have the router mounted so that the tool is perpendicular to the table in both the x and y direction. If you are off by even a couple thousandths you will have a tough time getting precise cuts. Notice above that with a 0.249" cutter my 0.500" slot was only 0.494". That's a little more undersized than you would expect even accounting for my undersize cutter. I recently changed the brushes in my router. I had to remove the router to get to one of the brushes. I was in a hurry and I didn't take the time to get everything perfectly square when I remounted the router. For many things it won't matter, but when you need exact cuts the machine has to be set up correctly. If I was going to run your project I would take the time to shim up the router in the holder to get it exactly perpedicular.

3: Looking at the picture of the caliper measuring the cutter, it looks like it is 0.008" undersize to me. Measure the shank of the tool. If the cutting tip is substantially smaller it may be time to retire the cutter (or just use it for roughing). On my end mill, the shank is 0.249" and the cutting tip is 0.249". I have it defined in my tool database as 0.249". For most things it won't matter, but when it does having it defined as the diameter it actually is will eliminate one more source of error.

Bottom Line:

Recalculate using an offset / conventional toolpath instead of a raster toolpath. Change the diameter of your tool to what it actually is at the point where it cuts the project. Adjust the router in it's mounting to make sure your are completely perpedicular to the table.

Try all that and then cut some 1" test squares and see how close you are. Measure in both the x and y direction.

Good luck. Hope it helps.

Ed

PapaBear60
Posts: 8
Joined: Wed Sep 22, 2010 4:11 pm

Re: Suddenly, I'm not getting accurate routes

Post by PapaBear60 »

Thanks, Ed. Will give that a try. By Offset/Conventional, I believe you mean the direction setting Climb/Conventional? I attached a picture. I'm using VCarvw 3.1 - need to upgrade to 5.x.

Thanks again. Will let you know how it turns out.

Dave
Attachments
raster.jpg

zac
Posts: 42
Joined: Tue Aug 10, 2010 8:48 pm
Location: NSW Australia

Re: Suddenly, I'm not getting accurate routes

Post by zac »

Hi Ed,
In your reply you mention the router needs to be perfectly vertical. Where do you place the shims ? And what is the best method to "measure" vertical
Wayne.

spinningwood
Posts: 191
Joined: Wed Aug 04, 2010 11:28 am

Re: Suddenly, I'm not getting accurate routes

Post by spinningwood »

Hi Wayne - Having the cutter perpendicular to the table is not critical for every job, but there are jobs where it is. If you are cutting out parts that have to fit together it's worth checking. If you are VCarving signs it won't really matter.

You can do an internet search on "tramming a mill" to get a lot of ideas on how to do this. Although we aren't talking about mills here, the concept is the same. The simplest would be to check a straight bit (or ideally a straight piece of drill rod) with a small square (that really is square). I shimmed mine by putting metal tape between the collar that holds the router and the plate that the collar is bolted to. I found that easier than trying to futz with loosening and tightening the router trying to nudge it vertical. When the router is loose it's hard to nudge it in just one direction. At least it was for me.

There's more than one way to check and adjust. Do what works for you.

Mine wasn't off much, but I'm getting better inlays after adjusting it.

Ed

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