View Full Version : Fixing the spoilboard to the support board

Wed 18 February 2009, 10:06
. . . .
Any suggestions on how to hold down the spoil boards? Spray on glue? I have no idea!

Wed 18 February 2009, 10:15
I use a roller and Elmer's wood glue.
Put a bunch of temporary screws or weight on top, then when dry, remove screws and weights.
Surface the MDF...when the sacrificial board gets to thin, I just add on top again!

Wed 18 February 2009, 10:17
Any suggestions on how to hold down the spoil boards? Spray on glue? I have no idea!

Woodglue (elmers, titebond etc) spread on with a roller, position board and weigh down with sand bags, timber, what have you...

Wed 18 February 2009, 14:41
Elmers Wood Glue.... cheap and it works.

Wed 18 February 2009, 14:56
Bondo spreader works a little faster. :)


Gerald D
Wed 18 February 2009, 20:43
We use a notched trowel to spread common glue:


Rad Racer
Sat 21 February 2009, 09:54
Does the spoil board get glued directly to the support board? If so, how do you remove\replace it when it gets too thin?

Gerald D
Sat 21 February 2009, 10:53
The spoil & support boards are of the same material, so it actually makes no difference whether we call one the spoilboard and the other the support board, nor does it matter how many joints/layers it has . . . .

You just keep surfacing down the wasted area on top until the whole thing gets too thin, and then glue a new layer on top. Sometimes you go through old glue lines, but always you watch out for not hitting the support board screw heads.

I think our tables typically show 2 or 3 glue lines, just above the heads of the screws.

Thu 28 May 2009, 01:40
Copied from elsewhere:

wait wait wait,... glue a spoilboard over the heads?!?!? Why would I do that? First,... how long does one usually keep a spoildboard for?!?!? 5 years seems like aloooooong time. I would think that any wood would curl up after abusing it for 5 years. I was thinking that i would use 3/8" countersunk hex head screws with some locktite to keep them tight. I wouldn't mind changing out my spoilboard everyonce in while if I do in fact tear it up. I would like to be able to remove the board.

Gerald D
Thu 28 May 2009, 02:14
Sometimes we resurface a spoilboard every week, taking off 2mm. In 8 weeks, a 16mm board is gone.

I wouldn't mind changing out my spoilboard everyonce in while if I do in fact tear it up. I would like to be able to remove the board.

Attaching the boards to each other with screws is a non-starter (you would need a million screws to attach it firmly enough).

Removable boards can be successfully attached by vacuum.

Otherwise the sacrificial boards are attached by glue and ground away by cutters, and time, and sawdust.

Thu 28 May 2009, 03:17
Ok,... so im confused. there's actually 2 boards?!?! One get bolts to table frame and then another gets glued to that one?!?! I thought there was just one board. Well,... technically after gluing the one board to the other, it will be one. So, one 3/4" board bolted to the table frame isnt enough?

Well,... if this is how it is then this changes things. If it's going to be like this then im not going to want my spoilboard bolts screwing into the frame. I would rather used carriage bolts embedded between the two boards sealed with a resin as you said. Fasten it down with nuts on the other side of the 302SB's.

Well,... seeing that we're on the topic of spoilboards. I think I should ask now. Does anyone have or use any "specialty" boards or jig like boards?!?! Im thinking no because alignment would be and issue but i know something can be done to atleast help remedy the problem.

The reason I ask is that I want to try to threadmill acrylic tubes with this router. The tubes are longer than what would fit under the gantry. The tube would have to pass through the board. I would need a way to mounting the tubes to the board fairly quickly. so that the ends can be threadmilled internally. I would need to figureout a way to add and remove this jig board so that it aligns everytime.

Anyone do anything crazy liek this with their router?

Thu 28 May 2009, 04:53
Glueing the spoilboard.

Yesterday, I discovered that my spoilboard except in the center of the board was not glued down. I had to pop the board loose and glue again. We have had rain for the last two weeks. Every day it has been raining which is unusual for us to have it rain most of the day every day. Daytona Beach to the North East has been declared a disaster area because of the flooding they have had.

Charles, the spoilboard is just that. It gets wasted and yes some glue is going to get on the bolts that hold down the support board. Eventually you replace the top board.

Thu 28 May 2009, 07:20
I have to order my spoil boards soon.
The supplier can only supply 16 & 18mm from his warehouse.
Am I on the right track if I glue it together like this? :


Gerald D
Thu 28 May 2009, 08:23
Glueing it up like that would be fine.

Thu 28 May 2009, 08:30
Thanks Gerald.
If I counter bore the second sheet as per drawing then I should have the clamping efect as well. I was just looking at my sketch again!:)

Thu 28 May 2009, 08:32

You can do what you have show but I don't think you need to do that. What the plans show is that you counter sink the bolts and washers in the first board. The spoilboard is the second board that sits on top of the support board. If you follow the plans you will have no problem with this set up.

As you use the spoilboard and resurface it you will eventually come close to the support board but you will not have a problem.

Gerald D
Thu 28 May 2009, 08:48
I relooked at the drawing today and see that I said 24mm max under the screwhead. That was because of the screw length. I should also have given a minimum and that would be 16mm. Anything thinner and I would fear for the head tearing out the bottom section. . . . . this after seeing it happen on our first table and finding it impossible to fix later.

Thu 19 November 2009, 23:50
Gauge holes.
I may suggest drilling holes right through your spoil board prior to gluing down. Use these holed as measuring holes. Step a vernier caliper down the hole will let you know how much spoil board is to go.
You could get fancy and place a thin film copper or Al strip between the boards at the bottom of the hole. run a lead from it out the bottom and use this as an electrically set datum for the bit.

Gerald D
Fri 20 November 2009, 00:45
That sounds way to complicated. The edges of the boards, and the glue lines, are visible all the time. Sometimes we put on a new spoilboard before completely cutting away the earlier spoilboard and end up with 2 glue lines. These things really don't matter in the bigger scheme of things.

Mon 06 September 2010, 07:28
I want to throw another wrench in this discussion...

What about dual use tables?

Seeing as a 4x10 or 5 x 10 support board and spoil board assy would be far too heavy for one man to remove and reinstall, I was thinking of using three or four sections, all fastened to their own tubular steel frame, that could then be slid in where the plasma slats would normally go, and then bolted to the main table...

So this whole gluing of the spoil board thing is problematic, unless the sections can all have their own spoil boards glued on them...

Imagine a 3' x 4' flat steel frame made of 2" x 2" square tube.. The support board would be screwed to this,,, Four of these would be slid onto the mechmate base table and bolted down with 4 bolts each... I was envisioning one large spoil board on top of the four sections, but now I can see now that unless they are vacuum sections, then the one piece is a non-starter..

So, if I were to build each section, with it's own spoil board glued on top, and then bolted each of the sections to the base table, butted end to end, and 'then' resurfaced all four sections as if they were one piece, would this work?

At some point down the road, the goal is to have two tables, one for plasma, and one for routing, but for a year or two, I will be forced to have the plasma table doing double duty... So the inherent problems with that are a bit unique...

Mon 06 September 2010, 09:55
Consideration -
The spoil board is what holds the table square in the horizontal plane. You may want to make a complete rigid frame that holds that true and a modular grid on top of that.

The UNCSA table was made so heavy and fully welded to take this into consideration. The table perimeter had to be strong enough (welded moment connections) to keep the diagonal vector from collapsing and "racking" the table out of square due to the lack of a spoil board.