Spoil Board Cut

[aliciaj]

Good Day, I need to make sure my spoil board is perfectly level. I have the big spoil board cutter bit. Do I select the 96x48 board and tell he Shopbot to cut it down, say at 1/2in. all around?

[steve_g]

Alicia…
In the interest of keeping the spoilboard around as long as possible… start by cutting as little as possible to level the spoil board. Try .060” to start with..
SG

[jerry_stanek]

Alicia…
In the interest of keeping the spoilboard around as long as possible… start by cutting as little as possible to level the spoil board. Try .060” to start with..
SG


I start with removing .010

[signtist]

Alicia, save this job because you will need it every time you resurface the table.

[steve_g]

Ha!... .060” as compared to .5! Anyway the SB spoilboard surface default is .030”. You’ll soon learn whether .01 or .03 or .06 is appropriate for how messed up your spoilboard is! At any rate we all agree that ½” is too deep!
SG

[GeneMpls]

Hi Alicia- welcome to a great board. For those of you who don't
know... Alicia is something of a legend in the hand painted sign
world (Letterheads) and good people. I am GeneMpls on the other
boards BTW. :D

[ssflyer]

Hi Alicia,

One thing to keep in mind - if you are referring to the starter bit set and the Onsrud spoilboard surfacer, I believe it has a maximum cutting depth of 1/8".

All the spoilboard cutters I've used have a very limited depth of cut.

[scottp55]

I agree with everybody:) Start super light like Jerry said--May give a really good indication of Z alignment problems before going further and get rid of any super high points. I'm one of the "Teeny" guys with a desktop but still Z-zero'ing to a low spot can come as a surprise when you hit a high spot, Can only imagine for you guys. Humidity changing 40% in 24 hrs here-back and forth.
Welcome.:)

[aliciaj]

So do I use the "Pocket Toolpath"? I have had my ShopBot for a few years now. mostly cutting simple shapes and letters. But I am going to start doing more work that reguires everything to be perfect. That's why I'm setting up a new spoilboard. The one I have now is made of particle board and is pretty worn out. Plus it is about off 3/8 on the far corners.

[ssflyer]

A few years back, Paco wrote an excellent surfacing routine. It let's you choose to raster in the X or Y direction, and with a few simple inputs lets you choose cutter diameters, depth of cut, stepover, etc.

If the first pass didn't go quite deep enough, when it ends it offers you the choice to run again at the same depth or half of that depth.

Pretty slick and easy to use. You can find it HERE. (http://pacosarea.blogspot.com/2007/02/surfacing-along-axis-shopbot-routine.html)

As Scott mentioned, I try to Z-Zero at the highest spot to start...

[scottp55]

Yep, Pocket toolpath, Do a Raster it's Faster. Make your rectangle large enough to get the corners without hitting the prox's (big guys can help you better). But for a Desktop with 24X18 for instance, I'll do rectangle 24.2X18.2 for a 3/4" bit and set the X,Y 0,0 lower left corner at -.1,-.1.
I max out the move speed at 4IPS for desktop as only cutting .01" to see the problems. I like to set starting point at X(Max) to check by eye I haven't screwed up a decimal point.:) Select "Use Vector Selection order" gives you a split second to hit spacebar.(Node edit-make start point).
Measure spoilboard cutter OD and enter exact #. Luck:)
Sometimes re-Zero to new height after first cut-sometime fudge halfway through with a re-Zero to see results. BUT best to re-Z at newly cut surface and change file accordingly. Light cuts at high speed seem best for me personally, but not dealing with your machine.

[scottp55]

Ron, Quick Aintcha:) Thought it might be nice as all surfacing routines are pretty much the same it seems. Was surprised to see fires were NOT fully under control. Your Shopbot OK? :):(

[scottp55]

General question to all, Would giving a Lacq or Tung coat with say 70% solvent to the MDF on the top surface accentuate or decrease deformation ? One side only, but high penetration? I THINK it would be BAD? Best to leave adaptation to RH equal?

[steve_g]

Forget sealers Scott, start using Medex… More resin = less swelling from humidity changes. Actually, I’d use Exteria if I could find it locally.
SG

[harryball]

I will be replacing my spoilboard... probably next week.

I will:
1) surface my current spoilboard down to the Extira which has the grid cut in it to get rid of it.
2) drop one sheet of 1" Ultralight Trupan on the bot and surface one side .02" at a time until I get a full cut.
3) remove it, apply yellow wood glue to the base and apply the Trupan with the surfaced side down
4) position the Trupan, throw a sheet of plastic over it and turn on the vacs
5) I'll load 2 or 3 sheets of 1" Extira on top for hold down
6) turn off the vacs and go home.
7) the next morning I'll remove the extira and the plastic and then surface the top by .02" until it is level.
8) then I zero to the corner of the table and run a cut file that drills a small hole at .75" x .75" to act as my on table zero reference.
9) then I run a cut file that will drill small 3/16" holes in 4 places along the Y and 4 places along the X for registration pegs made from 3/16" dowel. When installed they square up a 4x8 sheet on the bot along the 0 lines of each axis.

Done.

I'll run that until it's used up and repeat.

[steve_g]

Good point… I was assuming no vacuum hold down when I recommended Medex.
SG

[ssflyer]

I haven't found a good local source for Extira here. either. I've just been using MDF, as I'm not currently using a universal vacuum system. Trupan is another commodity I can't seem to find here, conveniently.

Scott - the fire's finally about 90% contained and has moved north of me. Pretty hairy driving out at 10:30pm, with both sides of the only road in and out of here on fire! :eek: Yep, ShopBot's good!

[scottp55]

Thanks Steve, used Big box store MDF(Lowes) as First time tiling, and it was a play on Bill Y's spoilboard. Noticed difference right off with clutching when doing threaded inserts:) Warping day by day. Will check out Medex.
Got BBPly correct dimensions, so will try that next. Nice thing about Desktops is you make Smaller mistakes:) You can Almost immerse a spoilboard in sealer:)

[scottp55]

Woops! Got stomped on:) GOOD Ron! Checked that road out on Google Earth. NOT many houses. You the Mansion on the hill? Or the guy by the stream?
You got WAY to many toys! 8 wheel drive? My wheelchair only has 2 on a Good day:)
Nice note Harry. Vac bagging is taken for granted now a days.(Would have come in handy for a couple of bow layups in the wildwater kayaks we made in the '70's with a "knife" prow). You guys are spoiled:)

[bleeth]

Dust from standard mdf (or ultralight) is no fun.
Extira dust is pure hell!

Considering the small size of a desktop as long as you weren't using a vac holdown you could use sheet pvc. More expensive, sure, but it's not like you are using a new spoilboard every other day!

[scottp55]

Dave, Hadn't considered PVC for dimensional stability, but can you use threaded inserts? Becoming addicted to the versatility it's giving me on proto's.

[scottp55]

Oops. Hit submit. Enough strength when swiss cheesing like this? Never used the stuff before. Does it thread OK?

[scottp55]

Sorry Alicia, HiJacking seems to be a horrible habit of mine! You OK on the toolpath?

[jerry_stanek]

Why not just use the table surfacer in the SB3 under tools.

[scottp55]

Jerry, I'm new enough to remember my first"Cut Part". That was mine.
I didn't know how to preview an .sbp, so it didn't teach me a thing.
I didn't know cutters, feeds,speeds, Nothing! and still knew the same after a cut.
Slower than raster and not very many variables(just did a surface routine yesterday using a keyhole cutter on the fly for a 3X6" area in 4 minutes vs. ?minutes changing bits and going VCP for a whole separate file and cutter with same results).
Also I think I remember that's a vector cut in the middle of the spoilboard, which is OK if you know what you are doing, but can be disastrous for a newbie vs. watching it dive towards your extrusions along your long axis, and you have a second to react.
Just newbie advice, WATCH in slow mo what it's going to do!
Sorry Jerry, Just beginners advice:)

[jerry_stanek]

Have you looked at the table surfacer utility it walks you through making a surface file

[scottp55]

Hi Jerry, Just did. Didn't see any raster options and couldn't tell if it was ramping or not, and on Desktop you Can't start off your material, especially when using oversized spoilboard to use the entire 24X18 cutting area.
Just easier to use pocket toolpath and control the variables better for us.
Thanks. Haven't tried that since September.

[bleeth]

Yes it will hold threaded inserts and should hold dimension fine. Like MDF the skin is denser than the interior. That means if you skin one side it may curl up just like MDF unless it is well secured to the base. What it won't do is swell/shrink under moisture change. Would not work as a spoilboard with a HVLP vacuum holddown though.

If you put a bunch of threaded inserts in it doesn't that defeat the purpose of it being a spoilboard, as cutting into it would total your bits on the inserts? (unless you sunk them deep enough to leave only PVC/MDF at the top).

I will say that my idea is conceptual in nature. I've only used ultralight for a spoilboard on big blue. There are a number of guys who use 1" as a base board instead of plywood due to its stability and even thickness.

[scottp55]

Thanks Dave, Inserts done from backside, so about a strong 1/4" of spoilboard surface with no inserts. should be able to get quite a few surfacings out of it. Flange made inserts very close to uniform insertion. Any vac jigs will be product specific.