Spoilboards 101?

**BoomerangInfo** · 10th January 2012, 01:38 PM

Now I have my CNC machine operating, i have to get it setup ready to run.At the risk of sounding like a complete idiot once again, I need help understanding how to setup and use a Spoilboard.

I know it's there to protect the Aluminium T-slot bed from damage as the machine cuts through your material, and from what I can see, MDF is the most common used material, which is good, as getting anything like Corian or other plastics would be difficult for me.

What I dont understand is the usage procedure. Most references I googled for talk about using it with vacuum, which isn't my case. Do I just cut a sheet the size of my bed, and drill some holes in line with the T-Slots to facilitate job clamping? Can I make it smaller than the whole bed size, given the router doesn't cover the whole area?

Then, as it gets marked by running jobs, how often do you resurface it? Only when your parts won't sit flat or clamp properly anymore? I see lots of talk about resurfacing, but none of them mention when to resurface.

Also with the resurfacing, given as I said about that the CNC doesn't cover the whole bed, and if the spoilboard does, then you'll end up with a higher lip around the edge of the board. Or is this the reason you would make the spoilboard the same size as your machinable area, or slightly smaller?

Sorry if this is blindingly obvious and my seeing eye dog hasn't pointed it out to me, but once again, the info I can find seems to start at step 2 or 3, assuming you already know step 1, which I obviously don't

Thanks. Russell.

**seafurymike** · 10th January 2012, 02:07 PM

I cut my board to the cutting size of the machine. In your case I would cut it a bit bigger for the T Slot track bolts and ensure the bolt heads are not in the cutting envelope.

Once you put it down, get a fly cutter (if you have one and your machine can accept it) or just a large slot mill bit and surface the cutting envelope. as you mentioned, once the sacrificial board doesn't keep the material flat, resurface it or replace it and repeat the above process.

Don't read too much into all of this. The best method is to get going and learn from your mistakes. The ultimate aim is not to rip through your router bed and to get the sacrificial board as close to flat as possible.

Then just enjoy making chips

/M

**SawDustSniffer** · 10th January 2012, 08:00 PM

if you cut all the way through or run around the edge of your material , you will need a sacrificial board ,
if you are edging your jobs you cant hold it by clamps , hence the vacuum clamp
any thing handy will do as a sacrificial layer , partical board , mdf , old solid core doors , Masonite, what ever is cheep

with the vacuum you would have to resurface it more often because the the cuts into the sacrificial layer will leak the vacuum ,
with clamps if it sits flat and doesn't rock its good , if it does find a spot where it doesn't to clamp it down

im not cutting around the edges or penetrating all the way through with my moulds ,so i dont need one

**BoomerangInfo** · 10th January 2012, 08:15 PM

Thanks guys.

When I finally get onto the boomerangs, they'll definitely be going through. The first stuff I'm trying though won't, but I don't want to take chances. I have some old chipboard, but will that be tougher on the cutters than MDF? I also imagine it doesn't surface well either?

Anyway, I'll look for some MDF next time I'm in town & see how it goes.

Russell.

**Ch4iS** · 10th January 2012, 09:15 PM

Chipboard was easy to cut last I cut it, definitely softer than MDF, I know it cuts clean with standard router bits (Straight 2-flute bits) but I'm not too sure how it'll surface.

Once I get things sorted with my own cnc I was planning to use HDPE offcuts as I worked out a cost of ~$25 for a 20mm thick spoil board (600x450 table), its mostly because I want to eventually add some sort of flood or spray coolant system.

**SawDustSniffer** · 10th January 2012, 10:01 PM

Originally Posted by Ch4iS

HDPE offcuts as I worked out a cost of ~$25 for a 20mm thick spoil board (600x450 table), .

where you getting your HDPE from , full sheet cost me $350 and i diced it up into 500x400 (2000x1200 sheet) @25mm , expensive stuff
let alone the 40mm thick sheet

**SawDustSniffer** · 10th January 2012, 10:16 PM

Originally Posted by BoomerangInfo

When I finally get onto the boomerangs, they'll definitely be going through.
Russell.

look at getting a vacuum table , ( make one !!!!out of MDF ) if you already have a very large compressor the venturi vacuum adaptors are economical

if not a refrigeration 3cf/min vacuum pump can be found on ebay for 100 bucks ,.
make an mdf board with trenches on one side , with a air connection glued in , glue your sacrificial layer to the top , and drill holes where your boomerangs will be , and where you want the waste to be held ( dont put holes where the cuts are ) ,
make a vacuum board for each G code program , and you wont have to resurface , the cuts are in the same place all the time

to remove clamps on one side and move them for each boomerang would be time consuming , with a vacuum table , you have a tap , clamp on clamp off

edit : the refrigeration compressors pump out an oil mist that will you off , the venturi will make a noise that will you off , no win situation , be prepared to put them out side the shed , also MDF will let a vacuum through , at work there cnc machine pulls the vacuum though a 18mm thick mdf sheet ( huge 3 phase vacuum pump ) , so sealing the sides and bottom with any paint , PVA glue / water mix , is important to get all the suction to the top

you will need a filter , and a tank would be handy , a true vacuum is only -14psi so an out of date GAS bottle will be fine as a tank , i use an 8cf/m vacuum pump on an out of date 60lt car LPG tank , with black irrigation 1/2 inch tube , with 1/2 inch irrigation taps ,tap
water is at over 60psi

**Ch4iS** · 10th January 2012, 10:22 PM

Best price I found was from a business selling on ebay

prime-mfg.com.au is their website.

Was Quoted ~$250 for a 20mm sheet 2x1M HDPE (~$125 sq/m)

------------------------------

From Plastix.com.au (They are within driving distance to myself)

Was Quoted ~700 for a 20mm sheet 3x1.5M HDPE (~$155 sq/m)

-----------------------------

For the offcuts I pay like $5 for a piece 100x700x20mm (~$70 sq/m) but also for the smaller pieces your still paying $5

basically just goes towards their beer money. I get the offcuts from CBC Bearings.

**SawDustSniffer** · 10th January 2012, 10:32 PM

Originally Posted by Ch4iS

Best price I found was from a business selling on ebay

prime-mfg.com.au is their website.

Was Quoted ~$250 for a 20mm sheet 2x1M HDPE (~$125 sq/m)

------------------------------

From Plastix.com.au (They are within driving distance to myself)

Was Quoted ~700 for a 20mm sheet 3x1.5M HDPE (~$155 sq/m)

-----------------------------

For the offcuts I pay like $5 for a piece 100x700x20mm (~$70 sq/m) but also for the smaller pieces your still paying $5

basically just goes towards their beer money. I get the offcuts from CBC Bearings.

yer same company post to NT must be the difference

**BoomerangInfo** · 11th January 2012, 06:47 AM

HDPE would be nice, but I think a bit expensive for me at the moment.

How well does it machine though? I'd have thought it might have melted from cutting friction? Or do you just have to set your feed speeds fast enough so that doesn't happen? I guess it would cut pretty fast.

As for the vacuum, it all sounds nice, but remember this is me you're talking to

I'm also at the point where I think I'll be overloading the power supply if I add mo motors running at the same time.

Russell.

**Ch4iS** · 11th January 2012, 10:52 AM

Originally Posted by BoomerangInfo

How well does it machine though? I'd have thought it might have melted from cutting friction? Or do you just have to set your feed speeds fast enough so that doesn't happen? I guess it would cut pretty fast.
.

I've never seen any sign of melting and I've cut at various speeds, it machines great on my mill, but still trying to achieve the perfect cut on my cnc router.

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