LDF thickness for spoilboard

[Greybarn]

Newbie question. What thickness LDF should I start with for the spoilboard? 1/2" or is 3/4" okay? Seems like 3/4" would reduce the amount of vacuum, as compared to 1/2". Anyone have a suggestion?
Thanks for the help.
Regards
Peter

[erik_f]

3/4" both sides surfaced is what I use. From what I have read here there is zero benefit going to 1/2" other than getting a shorter lifespan out of it.

[dana_swift]

Peter, Seems like 3/4" would reduce the amount of vacuum isn't correct, as there is almost no flow in the bleederboard. So the vacuum pressure at the top is almost identical to the vacuum pressure at the bottom.

As you get cut-through the flow increases and the top surface pressure drops as you are imagining, but so does the bottom pressure (where you can read the pressure on a gage). When I see my gage pressure drop to a point where I am concerned that the vacuum may be inadequate to hold the stock, I pause the router, put cheapo masking tape over all the cuts to re-establish the seal. Then I continue the cut. That works very well.

One problem can occur, when the bleederboard needs to be re-surfaced, a small cut through can spread out through the channels of the heavily used bleederboard and the pressure drops very fast. Its clear with experience that this is about to occur, so I just re-surface the bleederboard and that gets rid of the "ditches" that ruin the suction.

When the bleederboard is in good condition the 3/4 thickness is an asset because it does reduce the FLOW where you have cut through and the bleederboard is otherwise intact, so you lose LESS vacuum pressure.

FYI I use 3/4" Trupan on my vacuum hold down. Pictures are posted elsewhere if you want to look.

Hope that helps-

D

[Greybarn]

Thanks for the replies. I saw mention of Trupan being better than the LDF. Is this really true?
Regards
Peter

[harryball]

Trupan is better, but others will work.

If you get Trupan it WILL be branded on the edge. If there is no brand printed down the edge it is NOT Trupan.

The thicker the spoilboard the better things hold, seems backwards and I didn't believe it either until I found when I surfaced down to about 1/4" I had parts breaking free. The same job at 3/4" holds rock solid. I've heard some guys are running 1" spoilboards.

Arguments range on skinning both sides. I skin both sides and glue down on a 4 zone system pulled by 2 Feins.

If you glue/screw or whatever try to make SURE the board is flat and making full contact with your vac grid. When you do surface, do it with the vac on. This removes any bow up which will create low spots on the table once the vac comes on.

Be patient, learn from the forum, ignore us, learn the hardway, try to not clamp yourself to your own table, decide we are not all idiots (well some of us are) then contribute. :)

/RB

[Greybarn]

Thanks for the reply. I have learned to be cautious but I am sure that I don't even know what to ask sometimes about the Shopbot. Luckily, we are starting with simple 2D things. I am sure there is a learning curve there too but I am hopeful that it is not too steep. I will not be afraid to post when I have questions.
Regards
Peter

[jdervin]

So, my lumber yard sold me "Trupan", but since it's not branded on the edges, what is it? Is there anything I can do to prove their "mistake" and convince them to get me the real deal? Whatever it is, it is very much lighter than MDF, so I was fooled, but haven't affixed it to the plenum yet and have no idea how it will perform.

(I'm wishing this thread had come along before I ordered 1/2"...)

[harryball]

Others can verify, I have no reason to believe they would have stopped, but as of 6 months ago, all Trupan is branded down the edge. The lumber yard swore tooth and nail what was on the forklift was Trupan and I wouldn't take it. Finally a supervisor got involved, they took the UL MDF back and actually came back with Trupan, brand and all.

This is not mine, I found a photo on the web. But this is what the branding down the side of mine looks like.




/RB

[jdervin]

Thanks Robert, I'll certainly use that photo in a conversation with my lumber yard.

[rww]

All of the Trupan I have ever bought has had the printing on the edge. I use a generic light weight mdf and it works just fine for me.

[andyb]

Sierra Pine makes an ultralight MDF. That may be what you received. In my opinion, Sierra Pine is not as good as Trupan but close. I have used it on several projects. I use it for my spoilage board. The way I found out about Sierra Pine is, I ordered Trupan from a local lumber yard that gets their products from the big distributor in the area but Seirra Pine was delivered. It even had Trupan printed on the invoice. It turned out that the distributor sold all their UL MDF as Trupan at the Trupan price.

I live north of Atlanta. Since Trupan was so hard to find I just continued using Sierra Pine. I now get my Sierra Pine from a company that gets their material directly from the company and the price is really good.

Andy B.

[Gary Campbell]

Andy...
The Sierra Pine product I am familiar with which is Custom Wood Ultralite, like Trupan, is made from 100% Radiata Pine and our tests showed it to be very close, if not equal to Trupan.

We used the 18 and 25mm versions

[andyb]

Gary,
Yes, you are correct. Sierra Pine is Custom Wood Ultralite. As I stated, Sierra Pine is not as good as Trupan but close. For a spoilage board it works very well at a lower price than Trupan.

Andy B.

[loriny]

No idea what brand mine is but is an ultra light mdf from local lumber yard. No wholesalers carry it. Most big shops with huge blowers use standard weight they tell me. Mine works well with 2 central vac motors on all but the most twisted sheets.
Lorin

[bstern]

All my suppliers are no longer stocking Ultralight MDF in Charlotte.
Seems my only choice would be to buy a 40 sheet unit. (Truck load for Trupan) I don't have room or $ for that right now.

I was thinking that when my spoil-board (ultralight not trupan) got down to about 1/4" I would try 1/4 regular mdf on top. Skinned both sides of course.

Any thoughts on how this might perform?

FYI I cut 3/4 melamine exclusively.
With ultra light and a 10 HP Fuji pump - 7Hg - 200 cfm(i think).
I can cut some pretty small parts with the right strategy.
1.5" by 12" - Real happy with the performance now.


As a side issue:
I do allot of boring and sometimes the through holes in the spoil-board would get a little sloppy and cause chip out on through holes. I just upgraded to a boring unit with much less run-out. This should help some. But cant help but think a denser spoil-board could not hurt.

[Brady Watson]

I was thinking that when my spoil-board (ultralight not trupan) got down to about 1/4" I would try 1/4 regular mdf on top. Skinned both sides of course.

Any thoughts on how this might perform?

...But cant help but think a denser spoil-board could not hurt.

Bob,
"Regular" MDF leaves a lot to be desired in the 'reliability' department. Some off the shelf MDFs work just fine by just skinning both sides - while others have so much resin in them, that they will NEVER bleed, no matter how thin you go.

I remember visiting a shop in OH that had a big honkin' 25HP Cascade vac pump. The customer couldn't get LDF or Trupan, so he just used 'regular' MDF. After skinning both sides several times on a 3/4" board, it wound up being like 3/16" thick and STILL wouldn't bleed! This is because the MDF just had too much resin in it. He eventually had to order a few sheets out of state to get the right bleeder material.

Thinner does not mean better. There is virtually no difference between a 1/4" and 3/4" sheet of LDF or Trupan in terms of vac performance. It actually becomes detrimental when you get down below 1/4" since the sheet has a tendency to want to curl up on you - and that makes keeping it flat a challenge.

-B

[bstern]

Thanks Brady.

I made some more calls this morning and found not only LDF but "Trupan"
in Charlotte. :D Happy Happy Happy!

I am going to get some today. Only issue is they only stock in 4X8 3/4 or 5X12 3/4. I have a 4X8 Table today but, have upgrade to 5X8 on order.


Guess I will be piecing together off cuts from the 5X12 every 3rd spoil-board.

[bleeth]

Bob: You can scarf the 4 x 8 with a 1 x 8 also. A small shiplap which is glued when you flip to side B to glue it down and then skin it will work fine

[bstern]

Thanks Dave

[cabnet636]

so where did you find trupan in charlotte?

jim

[bstern]

A and M Supply

Let me know if you need contact info.

[matney_models]

Try this, They email right back and I will be going to Aetna Plywood and betting 4 sheets soon. I live in Erie, Mi. just north of Toledo, Oh
Aetna Plywood
1401 W St. Charles Road
Maywood, IL 60153
(708) 343-1515

Best Regards,
Rob Simonsen
Tumac Lumber Co., Inc.
Wk: 425 258-2217
Cell: 425 501-2058


Tumac Lumber Co., Inc.
805 S. W. Broadway - Suite 1700
Portland, Oregon 97205-3357 USA Tel : 503-226-6661
Fax: 503-273-2652
inquiries@tumac.com