Need feedback on resurfacing newly installed spoil board and calibrating FTC switch

[4Rider]

Hello Camheads,

had a good run of my first spoil board, almost 3 years, but it is a time for a new one. I am using WinCNC. I took the time and advise of fellow Camaster owners and installed threaded inserts in phenolic table on my Stinger III machine to hold the spoil board sections and also make for easier addition of new spoil board in the future.
My questions are do I surface new spoil board and then follow the procedure for calibrating FTC switch? Any advice on steps to resurface new spoil board like how to zero Z on the new spoil board? Can anyone share toolpath they are using for resurfacing spoil board?

Regards,
Viktor

[4Rider]

After some further search in the forums here found solutions. Was having "low boundary level on Z" and unable to lower the bit to touch the surface of the spoil board. G92 did not help but G49 to turn off settings did the trick. I have also found referenced in this forum Mick Martin's Spoil board Wizard which worked as designed. Spoil boar took two 0.01" passes with 10% overlap of 1.5" end mill to level and I am very happy with the results. I guess I am not a owner of the prized "swiss cheese" look spoil board anymore :)

Off to the next step to Recalibrate my FTC switch and will update the post with the outcome.

[sscooter]

Viktor,

First thing I see is you have a vacuum phenolic tabletop. I'll assume the threaded inserts don't leak vacuum and are just to locate your bleeder board and not hold down the spoil board. I would start with getting the spindle trammed dead to nuts perfect to the Phenolic top and then manually set a large spoil board bit (2.5") to the top of the Phenolic and shave it flat no more than 0.005 deep. You may need a G49 command if your tool won't reach the Phenolic top. As far as tool pathing goes draw 98 x 50 rectangle to match your tabletop and use a pocket raster strategy with a 75% step over. Use the Single Tool PP and design with Z zero to material top. Once complete change to a smaller bit that will work well with the FTC switch, lower it until it just touches your phenolic top and raise it 0.001" Now use the Calibrate Switch. Your Lo Boundry is now set to your Phenolic Top. Lower the bit back to Z 0.000. In WinCnC under Settings save this Z Zero position. Label it as Phenolic tabletop Z Zero. Install your Bleeder board with the threaded inserts. Since you have a 49 x97 tabletop use the largest bit again to resurface the bleeder/spoil board flat and true. Once again draw 98 x 50 rectangle to match your tabletop and use a pocket raster strategy with a 75% step over. Once again switch to a smaller bit that will work with your FTC. Careful lower this bit to your now very flat and true table surface and now use Calibrate Switch again. Your Lo Boundary is now set to your Bleeder/Spoil tabletop. The next step is to now check/set the low boundary setting in the WINCNC.INI [***********Soft Limits*************] lobound=z-0.005. Design your parts using the Z zero set to the Machine Bed (your tabletop) and measure and set the material thickness. Now ALWAYS use the tool change PP to save your *TAP files.

[Charlie_L]

If you use vacuum cut off on both sides of the spoilboard so the air can pass through the spoilboard and hold your work down.

[4Rider]

Sscooter, thank you for detailed instructions! lowering the bit to top is what I was missing and after that I struggled with the bit not wanting to go to the bottom with boundary error, so G49 command you suggested came handy to overcome the issue. I used 1.5" bit to mil the spoil board as it is the largest one I own. It took about 20 mins or for one pass on the spoil board, but I went with 20% overlap. After that just went as suggested with Calibrate switch using 1/2" bit. Everything worked great. Appreciate the help!
Threaded insets in combination with recessed nylon bolts are to keep the spoil board sections in place as I have vertical t-tracks and can't use whole sheet for spoil board. I use the vacuum to hold the spoil board sections true. No vacuum leaks. Threaded inserts are 1/2" going into 1" phenolic tabletop. Wish they offer threaded inserts installed as factory option.

[4Rider]

Charlie L,

I haven't milled both sides and while vacuum holds ok I see where your suggestion can increase holding power. Thank you!

[Jim Becker]

Charlie L,

I haven't milled both sides and while vacuum holds ok I see where your suggestion can increase holding power. Thank you!

The "factory" surface on most MDF is a bit polished and will not flow air as well as it needs to for vacuum table purposes. Cleaning off both sides insures maximum performance. It only needs to be a simple skim to remove the shiny surface that results when the material is pressed between rollers as it's manufactured.