Thread: How would you do this? Final adjustment of very thick bench legs

Originally Posted by Cgcc

I was also nervous about losing any meat as the height is already low and will be adjusted by solid feet.

I'd just construct the feet to suit the height difference?

Hi Bob

If I adjust the height by a different sized foot in one corner, won't it tilt the other corners away? Because the structure is rigid given the stretchers are all drawbored in, it still won't bring all 4 into co-planar will it?

I think I'd be bugged in perpetuity by throwing it all out of square as well...

If I am being thick and missing something please feel free to say so.

Chris

Cant just wedge a shim in there?

I would build a platform out of MDF encasing the top of each leg you want to trim which a plunge router can ride on. You would then clamp or temporarily glue the platform to each leg at the height you want it trimmed down to (i.e. 2mm) and then installing your widest bit and setting the depth of cut just a bee's before the bit protrudes from the base of the router. This should just leave enough for sanding.

You don't have one high spot; you have three high spots...

Put shims between all 4 legs and the benchtop until the benchtop is flat and level. Measure the shims and remove their thickness from each leg using KK's router jig idea.

The bench top is riding on three legs. Assuming the bench is reading level you need to remove the amount shown by the gap at the top of the forth leg from the tops of the other three. Easiest way to do this is run a sharp pencil line around the legs using the underside of the top as a guide for the pencil. Now cut off the excess to the same distance above each pencil line. Your bench should now sit on all four. This method is refered to as scribing.

Thanks mate that does seem the method for cutting... the annoying thing is that at 150mm x 85mm it's a really wide span, so I think I'd have to have to do it in two sections so have enough registration on the router, then chisel out a bit in the middle - do-able though.

Originally Posted by KahoyKutter

I would build a platform out of MDF encasing the top of each leg you want to trim which a plunge router can ride on. You would then clamp or temporarily glue the platform to each leg at the height you want it trimmed down to (i.e. 2mm) and then installing your widest bit and setting the depth of cut just a bee's before the bit protrudes from the base of the router. This should just leave enough for sanding.

A good idea, but this is intended to be a workbench that has pride of place for me and the leg will be flush with top so I think it'd always bug me knowing it was there!

Originally Posted by havabeer69

Cant just wedge a shim in there?

I like Rusty's method.

Once all legs have been accurately scribed, I would trim them down to the scribe lines with my LN low angle jack plane.

Theoretically, a block plane is used for this type of end grain, but the size of those legs is daunting. I would freshly sharpen the LAJ without a microbevel to give it as low a cutting angle as possible.

Once you have the top of the legs fixed, then you can focus on the bottom of those legs!

Thanks Chief, I think I will do that. I've seen the other suggestion re scribing but I am concerned about (my) accuracy with a pencil line when we're talking about a mill or two.

Any reason one couldn't use pieces of paper to make up a shim, then measure? I'd need a pretty large shim and without a table saw or similar I don't really have anything handy to safely cut small shims without much faffing around.

Did you check for racking while gluing up the frame? also you could do a 3,4,5 to see if you are at a true 90 degrees angle between the stretcher and legs (better than using a small square)

Is the bench in the position where it will live if not move it to that location and see if it rocks on the floor, if it rocks then it will need scribing to the floor (making sure you scribe it level), best to do this in the position it will live because your floor could be different elsewhere.

Once it is scribed to the floor check your top again, if you still have a gap, draw a pencil line 50mm down from any leg (this will become your Datum reference point) then use a level from your Datum and transfer the Datum reference to each leg, this will tell you which legs need adjustment.

You could do it with a sharp handsaw (8 t.p.i.) but first make yourself a mitre box the same section as your legs with a 90 degree cut in it, it would be best for the mitre box to be say 75mm higher than you leg section this will allow you to put your handsaw in the 90 degree pre cut slot above where you want to cut, by using a mitre box it will allow you to cut off a small sliver of wood accurately.

Hi Kahoy

A late second thought

I think the width of 150mm (what was I thinking) would actually let me use the parallel guides and fence - so what does seem doable is to run the router (taking off eg 0.4mm at a time) with the fence, leaving say 1/2" fore and aft to keep the registration, then chisel/flush saw the remainder away...

I think I'll be working on a scrap piece first either way.

Originally Posted by KahoyKutter

I would build a platform out of MDF encasing the top of each leg you want to trim which a plunge router can ride on. You would then clamp or temporarily glue the platform to each leg at the height you want it trimmed down to (i.e. 2mm) and then installing your widest bit and setting the depth of cut just a bee's before the bit protrudes from the base of the router. This should just leave enough for sanding.

Originally Posted by Cgcc

Thanks Chief, I think I will do that. I've seen the other suggestion re scribing but I am concerned about (my) accuracy with a pencil line when we're talking about a mill or two. ...

I would never use apencil - a marking knife is so much more accurate. Lots of info on Derek's website.

... Any reason one couldn't use pieces of paper to make up a shim, then measure? I'd need a pretty large shim and without a table saw or similar I don't really have anything handy to safely cut small shims without much faffing around.

This will work well.

But a more direct method is to use the underside of the benchtop as a reference surface and then just measure down the legs a uniform distance. A 2 or 3mm spacer is probably all you need.

Thanks for the reply - the base is all fine. It's your average garage floor where once feet are reasonably standing flat I'd shim between legs and floor for any slight deviations (given it's as liable to be the floor uneven as the legs).

I didn't check for racking for the simple reason that once the mortises and tenons were test-fit, they were so large, and being drawbored in, I don't think there is anything at all I could have done to affect the geometry at the glue-up stage.

Originally Posted by Camelot

Did you check for racking while gluing up the frame? also you could do a 3,4,5 to see if you are at a true 90 degrees angle between the stretcher and legs (better than using a small square)

Is the bench in the position where it will live if not move it to that location and see if it rocks on the floor, if it rocks then it will need scribing to the floor (making sure you scribe it level), best to do this in the position it will live because your floor could be different elsewhere.

Once it is scribed to the floor check your top again, if you still have a gap, draw a pencil line 50mm down from any leg (this will become your Datum reference point) then use a level from your Datum and transfer the Datum reference to each leg, this will tell you which legs need adjustment.

You could do it with a sharp handsaw (8 t.p.i.) but first make yourself a mitre box the same section as your legs with a 90 degree cut in it, it would be best for the mitre box to be say 75mm higher than you leg section this will allow you to put your handsaw in the 90 degree pre cut slot above where you want to cut, by using a mitre box it will allow you to cut of a small sliver of wood accurately.