spoil sheet support for a MTR Thermwood

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Neville Bastian
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spoil sheet support for a MTR Thermwood

Post by Neville Bastian »

Not sure what you call the sheet of mdf you have under your spoil sheet.
Mine is really old, like 12 years old.
Buying some new sheets in as my bed is 2200mm by 3600. When we did the sheets first time we told to seal the edges with oil based paint and make sure the rubber seal is not disturbed.
Is there any other tips users have done to increase the performance of the table hold down?
Have wondered if I should router any grooves on the underside to increase the vacume performance?
Although I have the 2200 table I only use 1800mm of it. Should I leave that exposed or do something with that. A bit worried about the pushoff bar grabbing laminate or similar.
With the mdf flycut sheets does everyone just leaving them loose on the bed and rely solely on the vacume to hold them down when skimming/ fly cutting them?
If someone has asked the above before, please just flick me the link.
Regards Neville
Neville Australia
Jeremy Schiffer
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Re: spoil sheet support for a MTR Thermwood

Post by Jeremy Schiffer »

Hey Neville,

We decided to experiment with that as well, and tried drilling holes in our spoil board. It seems to work very well. ProTip: Don't forget to flycut the spoil board (on both sides) before you drill the holes! Once drilled, it of course won't lay flat for flycutting anymore. I think I put the holes at 32mm centers, 5mm diameter, because why not. Ended up with something like 5,200 holes in the 5x12 table.

On top of the spoil board we just use 1/4" MDF as a wasteboard. We don't attach it in any way, it just lays there. Though, inadvertently, there is tape residue on our spoilboard from other projects that we do, and the waste board sticks to that enough so it doesn't slide around... :mrgreen:

As for the unused portion of the table, we use a 12" wide piece of 1/4" melamine to cover it. But we don't have the fancy-dancy pushoff bar to worry about either. We still have to unload by hand. In the snow. Uphill both ways.
spoil board.jpg
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Neville Bastian
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Re: spoil sheet support for a MTR Thermwood

Post by Neville Bastian »

Thanks Jeremy. Good tip.
I do have a hold down issue with the waste board we fly cut lifting a bit in the 0,0 area. Your solution may well solve that. I believe the cutcentre machine has 4 sacrifical wooden dowells in each corner that hold the waste board in position. That would help with hold down and the push off bar sometimes grabbing the waste board sheet.
I guess you dont want the push off bar which should be able to be fitted. I think it saves at least 10 minutes each cycle. While its cutting the next sheet the operator is retrieving parts and stacking them away ready for edging. We dont have auto labelling. That would be great as the number of new operators who cant position that label is amazing. Then parts get edged incorrectly.

You say its snowing Georgia? Maybe the MDF dust around the machine is like snow. 8)

Regards

Neville
Neville Australia
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Re: spoil sheet support for a MTR Thermwood

Post by Tommy Wieler »

Instead of investing in a push-off bar, try building a table the same height as the CNC table. Then just use two waste boards. As soon as one sheet is done cutting, push the whole wasteboard off onto the neighboring table, then place the second wasteboard onto the machine and keep cutting while you're placing the labels and offloading the first wasteboard. Works great for us.
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Re: spoil sheet support for a MTR Thermwood

Post by Brad McIntosh »

Neville,

Here in Canada, most of our clients refer to the primary 3/4" (19mm) MDF sheet that sits on the vacuum plenum area as either the "SPOILBOARD" (old) or "TABLEBOARD" (new). The daily sacrificial board (usually 3/8" / 10mm) is called either the "SPACER" (old) or "WASTEBOARD" (new).

Are you saying that your main SPOILBOARD/TABLEBOARD has not been changed in 12 years??? If yes, read on. If no, then ignore what follows...

Using the same main SPOILBOARD/TABLEBOARD will lead to MAJOR vacuum issues as the fine sawdust will clog the surface and hinder the vacuum draw through it. Also, the manipulation over time of the WASTEBOARD on top of it will "buff" the surface closed. Both things will degrade your vacuum efficiency.

We suggest that our clients lightly resurface the main SPOILBOARD/TABLEBOARD at minimum once a month to allow it to be "opened up", as well as, even things out possibly caused by uneven swelling or shrinkage due to humidity changes (wet/dry seasons).

** Remember that if you are changing out the main SPOILBOARD/TABLEBOARD that you surface BOTH sides of the board so that the closed, denser factory surfaces are "opened up" to lessen any vacuum draw restriction.
Brad McIntosh
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Neville Bastian
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Re: spoil sheet support for a MTR Thermwood

Post by Neville Bastian »

Hi Brad,Sorry for the delay in replying. I must have missed a email message that you had replied.
Yes its from 2008 a great year if your trying to sell a house below cost.
I was led to believe this was special MDF and had to come from the USA. Upon recently checking the density, it was available in Oz.
The suction has deminished so will go with your skimming suggestion.

Seeing you bought up the suction issue. I have two 360 Becker pumps. I guess 360 means cubic meters.
What diameter pipe would you install from pumps to the Thermwood?
Also is a storage vessel no advantage between pumps and Thermwood. Just thought that may give a extra jolt hold down effect?
The other question is ,should you have a air filter on the incoming air to the pumps? I havent but I see it is a optional extra from Becker.

The 10mm waste board. As you get to the centre of the 10mm it gets very fiberous. What thickness would you go before you discard this?

Now a totally non Thermwood question. What do you do in Canada with your waste material. Is it land fill or do you remanufacture it back into new board like I believe Germany does?
Regards Neville
Neville Australia
Brad McIntosh
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Re: spoil sheet support for a MTR Thermwood

Post by Brad McIntosh »

Neville,

I work more on the software and general operational side of the Thermwood routers, but here is what I have for you:

TABLEBOARD Material -
  • The "special MDF" from the USA is probably a form of LDF (Light Density Fiberboard) or ULDF (Ultra-Light Density Fibreboard). It is in fact special in that it is more porous and allows the air to pass through it very easily.
  • But it, like all fibreboard spoilboards, also acts as a fine filter for the micro-fine sawdust and as such will get clogged up. So it would need to be "opened up" periodically.
  • Being so porous, we found that the vacuum losses in areas of the table that did not have a stock material covering it, reduced the overall vacuum effect on that material.
  • Most of our clients use an MDF with higher softwood composition. The medium density helps to keep the vacuum more evenly distributed.
Vacuum Pumps -
  • The two (2) Becker pumps are probably moving about 5 cubic-metres/minute (180 cfm) - each. That is a total of 10 cubic-metres/minute. (About 360 cfm). We have similar (yet different brand) of pumps here in our demonstration lab, and we run a single 100mm (4") OD pipe from the two pumps over to the Thermwood.
  • The brand of pump that we distribute with the Thermwood routers here in Canada does have a filter integrated into the vacuum input on both units.
WASTEBOARD -
  • Some clients like to push it when it comes to machining the WASTEBOARD. You can determine for yourself when to stop resurfacing when you see the corners start to "thin" and curl. Many stop when they get close to 4mm.
  • I might tend to stay away from drilling a grid of holes through your WASTEBOARD. I have seen it tried and it does not appears to produce the improve vacuum being sought. These holes have more of a tendency to allow the vacuum to escape more quickly though uncovered "holes" and diminishes the overall vacuum under the sheet/parts.
  • As with a new TABLEBOARD - Always initially surface BOTH sides of a new WASTEBOARD to remove the denser "surface skin" and "open up" the fibres.
  • Do NOT use a HDF or "hardboard" material (Masonite here in Canada) for your WASTEBOARD.
Scrap Wood Material -
There are areas of the vast country where -
  • It will go to landfill with the rest of the garbage.
  • If the client keeps the "sawdust" and scrap material uncontaminated by "garbage", etc - there may be "wood recyclers" that will pick up the material (use in recycled paper products??).
  • We do have a few smaller rural clients that burn their waste in boilers to heat their plants in winter and generally provide hot water.
Hope this helps. Take care...
Brad McIntosh
CNC Automation

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