Steps in Spoilboard surface when resurfacing

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Steps in Spoilboard surface when resurfacing

Postby CyberBiker » Sun Sep 24, 2017 9:39 am

stepsinspoilboard-1080.jpg
Picture showing steps in spoil board
Machine: Shark HD Extended
Software: VCarve 9.0
Spoilboard: 3/4" MDF 24 x 48
Bit: 2" Whiteside Surfacing Bit, 1/2" shaft

Problem: When I try to "flatten" my spoil board, I get steps across the width of the spoil board. This doesn't seem to happen if the bit runs the length of the board.

Picture, .crv & .tap files attached.


Thanks for your help
Dave
dhdeitrick@mac.com
Attachments
Re-Surface.tap
Toolpath I am using
(3.83 KiB) Downloaded 7 times
2x4SpoilboardHoles.crv
VCarve file used. Exported & used Resurface path by itself.
(539.5 KiB) Downloaded 10 times
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Re: Steps in Spoilboard surface when resurfacing

Postby sk8nmike » Mon Sep 25, 2017 9:59 am

your router mount is tilted. Try adjusting it or adding shims to get it parallel to the table.
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Re: Steps in Spoilboard surface when resurfacing

Postby CyberBiker » Tue Sep 26, 2017 6:26 am

Thanks, I will check that out. Since it is a new machine (2 weeks), I will contact the manufacturer about how to fix the problem.

Dave
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Re: Steps in Spoilboard surface when resurfacing

Postby Kayvon » Tue Sep 26, 2017 9:44 am

There's probably a tilting problem also, but it looks like the entire pass is more shallow in one direction than the other. You may be taking off more material in a single pass than can reliably produce a smooth surface at that speed.

After you finish the surface operation, go back and complete it again as a finishing operation, but only removing a small amount (maybe 0.005"). See if you end up with a smooth surface after that. Use a smaller step-over, too, which will reduce (not eliminate) the effect of any tilting problem you may have.
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Re: Steps in Spoilboard surface when resurfacing

Postby CyberBiker » Wed Sep 27, 2017 5:29 am

The pass depth I used was .005 to start with.
How shallow of a pass can I realistically get to work?

Thanks
Dave
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Re: Steps in Spoilboard surface when resurfacing

Postby Kayvon » Wed Sep 27, 2017 11:12 am

0.005" is plenty shallow already. I typically cut down aggressively until I'm past the previous spoilboard damage, then take a shallow finishing cut afterwards. Sounds like you're already doing that.

My router has some tilt to it that I've not been able to get rid of. I need to find a sufficiently thin shim. Meanwhile, I use a bit of sanding to even it out after the resurfacing. Your problem looks worse, however. Maybe bad tilting?

Check out this thread for a good approach to tilt testing. I don't have the capability to make something like this, but I'd be interested in purchasing one from someone who does.
http://www.cncsharktalk.com/viewtopic.php?f=7&t=4684
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Re: Steps in Spoilboard surface when resurfacing

Postby CyberBiker » Wed Oct 04, 2017 5:51 am

After some back & forth with Next Wave Automation, and a bunch of videos, starting wth https://www.youtube.com/watch?v=DmuipSuDNAs recommended by Next Wave Automation about Tramming (also good advice from CNCNutz on YouTube) I discovered that from front to back, my 2" bit was different by about .030", sides seemed OK. I have a dial caliper from another device, so I made a tramming bar from pieces of 1/2" and 1/4" aluminum rod. 1/4" holes were drilled & tapped into one side of the 1/2" rod and the opposite end. The 1/4" rod was threaded, screwed in to the side of the 1/2" bar and put in the router. The Dial indicator was bolted to the end of the 1/2" rod. Note that the. maximum radius between the router and the carriage is about 3.5" so the tramming bar will not work if it extends the dial indicator farther than that.

Since I had one, I used a granite sharpening block (9" x 12" x 2"). After squaring the X & Y axes, I began shimming the router bracket between the lower 2 bolts (needs to tilt the router towards the back of the machine). Each shim change required removing the router, loosening or removing the mounting bracket from the mounting plate, inserting the shim, tightening the mounting bolts, re-installing the router and rechecking the X & Y axes for flat.

It took several tries, and about 40 layers of aluminum foil (nearly .050" total thickness) to get the same reading with the tramming bar to the rear as the front, but it finally happened.

Then I ran a very light flattening pass with the 2" router bit twice and got rid of the original steps and had a good, tho not perfect spoil board.

Thanks to those who made suggestions here and to Matt at NWA for pointing me in the correct direction.

Now to get some projects going.
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