Laminating Hardboard - Can I get a very flat uniform thickness result?

[Rush Paul]

Has anyone glued (laminated) 1/4" or 3/16" hardboard? I want to make some dovetailed replaceable inserts for the fence of my cross-cut sled and I'm thinking of laminating two 3/16" thick strips of hardboard, putting their waffle non-tempered sides together, to end up with a 3/8" thick part that I can screw to the laminated plywood fence of the sled. What I'm concerned about is whether I'll end up with a uniform thickness for the length of the lamination. So, just checking to see if anyone else has tried this and with what success?

Yes, I could use 3/8" Baltic Birch plywood, as with the rest of the fence, but I'm looking for an alternative that might be more durable in this location. Alternate suggestions welcome!

[glenn bradley]

Single sided tempered hardboard is not very consistent in thickness so your result will reflect that. Double sided tempered hardboard is a bit more consistent. You could put a micrometer on your material oriented as you plan to laminate it. Check every inch or so along an edge and see if that level of deviation is acceptable to you. I use 1/4" MDF for my inserts but I would think that your hardboard should work.

Matchfit Sled 2 (56).jpg

[Richard Coers]

I'd use hardwood. Machining hardboard to a sharp bevel edge will not give a very good result.

[Rush Paul]

Thank you. I suspected the hardboard would not be as consistent in thickness as one would want. Plus, laminating it would add a whole additional variable. MDF may be the right solution here. As Richard suggests, hardwood would be easier to get consistency, but I'd be concerned about longer term dimensional stability. So, options seem now to be either MDF or Baltic Birch given the suppliers I've been able to identify online and in town. I've been hoping to find an online supplier of HDF panels in shippable cut sizes, but no luck so far.

Glenn, thanks for the picture of your sleds hanging on the wall. They are inspirational!

[glenn bradley]

Glad the sled pics helped. If you have a local home store, they generally carry "handy panels" of 1/4" MDF. I have also used 1/4" melamine laminated MDF as the white makes things very visible. Actually all of my sleds are set for the small additional thickness of the melamine MDF. For regular 1/4" MDF I just shim with a thickness or two of tape. The inserts are wear parts so I make them by the batch.

I do want to point out that you will have to start and stop your cut in the middle of the insert if it is only held in place by the dovetail geometry. Once cut through (at one end or all the way) there is nothing to keep the kerf opening stable . . . yes? If you have figured a way around this I would like to see it. I have always been able to find screw positions that are where the blade can never reach but, no screws would be even better.

[Rush Paul]

Yes, I understand the insert cannot be cut all the way through. This would only be for the back fence where I will have enough height to exceed the maximum height of the blade. The zero clearance bottom for the sled will be made of two sliding panels held in place with machine screws into t-nuts inside slots, with the heads of the machine screws sitting below the bottom's surface.

[Warren Lake]

duron tempered hardboard was the highest quality hardboard I could buy at the time. When cut up 100 sheets it was clear that the tolerance was off even on that quality material and had to buy a small wide belt sander to bring it all to a thickness that would work for the job I was doing. It was the best at the time and even at that thickness varied.

[Rush Paul]

Many thanks to all who replied. I found an online source for 1/4" double sided melamine MDF and will plan to go with that solution.