Thread: MDF, Bunnings Plywood or Birch Ply for Jigs

Originally Posted by Bucky

I have ordered a sheet of 16mm Valchromat through Bunnings to make jigs, etc.

What was the cost? Thanks

Funny I came to forum because I am in the middle of building a Table Saw sled and my ply is warping before I even finish the job! I might give this Valchromat a go! Out of interest, which thickness might work best for a Table saw sled?

Originally Posted by mote

Funny I came to forum because I am in the middle of building a Table Saw sled and my ply is warping before I even finish the job! I might give this Valchromat a go! Out of interest, which thickness might work best for a Table saw sled?

For MDF typically 16-18mm is probably most common, depends on design. I haven't made mine yet but the fence system is going to be 6mm thick Aluminium equal angle as to assure completely straight cuts & it will also be interchangeable with other sleds.

I'll post some pics when I've made it.

Oh nice, I hadn't thought of using Al angle. What do you plan on sealing the MDF with? Thanks again

Originally Posted by mote

Oh nice, I hadn't thought of using Al angle. What do you plan on sealing the MDF with? Thanks again

I got some old F&W varnish that I'll thin down and chuck at it I think

OK cool, so oil based instead of water based. Thanks again

Originally Posted by mote

Funny I came to forum because I am in the middle of building a Table Saw sled and my ply is warping before I even finish the job! I might give this Valchromat a go! Out of interest, which thickness might work best for a Table saw sled?

Hi Again Mote,

I forgot to ask, what plywood did you use?, the stuff that warped?.

For what its worth, I have used shellac with good results on MDF, especially the edges. You can sand it in under an hour, and the second coat is smooth to the touch. Thin shellac followed by wax on the flat surfaces works well too, but if its likely no better than varnish if you have that on hand.

Regarding birch ply: 37 years ago I made a hi-fi cabinet and was emphatically urged to use baltic birch ply for the doors. I did, and covered them in bookmatched rosewood veneer on both sides with a solid edging. That thing was fantastic for about two years, then the doors warped. Even the premium grades of plywood can warp.

Originally Posted by EagerBeaver71

I forgot to ask, what plywood did you use?, the stuff that warped?.

Oh yes! I cut an older piece of 12mm plywood that had not bent over 5 years ... sure enough it bent within hours of cutting and sanding. I was about to buy MDF then realised that the weight of the fence (2x25mm pieces of ply laminated) was enough to remove the warp.

I finished the sled and today made a mitre saw stand. The sled was perfect!

I was lucky the weight of the fence removed the warp.

Originally Posted by Greg Q

For what its worth, I have used shellac with good results on MDF, especially the edges. You can sand it in under an hour, and the second coat is smooth to the touch. Thin shellac followed by wax on the flat surfaces works well too, but if its likely no better than varnish if you have that on hand.

Regarding birch ply: 37 years ago I made a hi-fi cabinet and was emphatically urged to use baltic birch ply for the doors. I did, and covered them in bookmatched rosewood veneer on both sides with a solid edging. That thing was fantastic for about two years, then the doors warped. Even the premium grades of plywood can warp.

G'day Greg, Very interesting to read about the baltic birch ply warping only after 2 years, thats shocking!. It seems the Americans swear by the stuff but I've only ever read how much of a problem the stuff can be here in Australia.

Originally Posted by mote

Oh yes! I cut an older piece of 12mm plywood that had not bent over 5 years ... sure enough it bent within hours of cutting and sanding. I was about to buy MDF then realised that the weight of the fence (2x25mm pieces of ply laminated) was enough to remove the warp.

I finished the sled and today made a mitre saw stand. The sled was perfect!

I was lucky the weight of the fence removed the warp.

What sort of ply did you buy? (I'm a poet!). Also where did you buy the stuff from?.

Originally Posted by EagerBeaver71

What sort of ply did you buy? (I'm a poet!). Also where did you buy the stuff from?.

Good question! it was 12mm C/D plywood I bought at Bunnings!!! I was there buying something else and and noticed that the C/D ply had what looked like a B or maybe even A grade finish! I grabbed two sheets. It was a bargain. Nothing like the C/D crap that is pushed out at the moment.

One of these sheets become a dog Kennel years ago. A month or two ago I broke that down and realised how well the ply had maintained its shape and finish. It was this ply that became the sled It was better than the newly purchased 12mm B/C i bought at bunnings a fortnight ago.

If I have to build any jigs in future it will be MDF. Not keen for the wait to finish it though.

Originally Posted by mote

Oh yes! I cut an older piece of 12mm plywood that had not bent over 5 years ... sure enough it bent within hours of cutting and sanding. I was about to buy MDF then realised that the weight of the fence (2x25mm pieces of ply laminated) was enough to remove the warp.

I finished the sled and today made a mitre saw stand. The sled was perfect!

I was lucky the weight of the fence removed the warp.

Nice one mate, you don't mess about hey!. Any chance of some photo's up on here to take a look?.

Originally Posted by EagerBeaver71

Nice one mate, you don't mess about hey!. Any chance of some photo's up on here to take a look?.

Yeah I will! It is based off the "Fix This Build That" table saw sled ... How To Make A Table Saw Sled (FREE Plans) | FixThisBuildThat

I don't know what I have been doing all these years without one!