screws for faceplate

[marcros]

I am going to make a disc sander for my lathe. I have a spare faceplate, but what size screws should I use?

The 9-10" disc is going to be 3/4" ply. It can be double thickness if need be.

I also have a spindle tap, so can tap a piece of hardwood and glue the faceplate to that if need be.

 

[offanonone]

Common sense would suggest the biggest guage that will fit in the hole, and as long as possible without poking through t'other side.

So probably something like 1 1/4" x 10 roundhead.

 

[Dalboy]

Make it double thickness but before sticking together put some T nuts through the one fixing to the faceplate then fix the second layer to the first trapping the T nuts (which need to be recessed) that way you can use countersunk machine screws to attach the plate to the face plate. This in turn lets you to remove the sanding disc to use the faceplate at a later date with no fear of the screw holes becoming worn through the removal and fitting stages. The top plate can be as thin as 1/4" as it is strengthened by the first plate

 

[Phil Pascoe]

I found the best thing to do assuming you have eight or more holes is the use very good quality screws, but to keep them short. I use MDF and pva to stick the paper and treat the mdf as sacrificial - after you tear a sheet off it you skim it back flat if needs be four or five times before replacing it. I found a bonus with this is that you can very slightly feather the edge of the mdf so if you want to put something flat on it, it doesn't scar so much if you catch the edge.If you're not going down this route of course you can use full length screws. I have one hole in an odd place on a rib of the faceplate - I'm in the habit of putting one mounting screw through that so if I ever have replace anything (no matter how unlikely I thought it) the holes are irregular.

 

[SVB]

Also tip I was given was to countersink both sides of the faceplate holes, i.e. including the side the wood is on. This stops the small bits of wood displaced by virtue of screwing the screws in, causing the wood to not sit flush on the faceplate.

 

[Phil Pascoe]

That is sound practice when screwing any two things together, even just two bits of wood. It takes very little to hold two surfaces apart.

 

[marcros]

thanks everybody.

Next question- what percentage of a (10") disc sander is actually useful- I am making a jig to hold in the tailstock to square pen blanks, but how close to the centre of the disc is usable?

 

[Phil Pascoe]

The inside few inches aren't much use - I tend to start anything dirty there, if it clogs it doesn't really matter much. A crepe belt sander cleaner works fairly well on them, but use it across the disc or with the disc hand turned in reverse.