Thicknesser Paralellism

[rosinante]

Hi all, after much faffing I have with aid of a dti determined that the cutter head on my inca thicknesser table is 20 thou out from side to side, it is unlikely that the cutter head or table can be adjusted so I will have to off set the blades, Q will that cause too much vibration , also what is an acceptable tolerance, the machine is only used as a thicknesser and the tables are not reliable enough as a datum surfaces , thanks for your thoughts
Chris

 

[sunnybob]

Thats only a half mm, over what, 30 cm?

Are you making stuff that will show that amount of error?

If you run one side through, then turn it in both planes (top to bottom and front to back) and run it through again it will even out.

Remember, it is wood, wood will move. That kind of tolerance would only show up in top notch furniture.

 

[Steve Maskery]

Reversing the direction will give you tearout. 0.5mm is enough to be a PITA. But a planer is only a prep machine, and 0.5mm can be dealt with with a hand plane.
I don't know the mechanics of the Inca, but my Kity was out by a light-year when I got it. It was successfully set up, by an ex-Chinook engineer (who had never seen a P/T before in his life) at the cost of 16 hours labour. Fortunately I did not have to pay the bill!

If the bed is chain driven, it can be set up correctly, but it is not quick or easy to do, I'm afraid.

 

[rosinante]

0.5 mm is indeed a pita when making frame members it shows on the joints , yes it can be sanded out or planed but I want it to be as right as possible , I think I will adjust the blades to minimise the error perhaps by 50 % as I cannot be sure the errors don't change at all bed heights .I rarely plane at full width and the errors are noticabe at 50 mm
thanks
Chris

 

[dzj]

Any radial play in the bearings?

 

[deema]

I don't know the machine, however if you can't shim the bearings to attain alignment can you shim the table? Feeler gauges make brilliant shim material

 

[marcros]

what is the state of the table? if the tables is all over the place, then it isn't going to make much difference even if the cutter block is perfect. is it flat? The table and the block need to be parallel to each other. Could you put a shim along one edge of the table to correct it? I don't know if you could get a decent sized sheet of something that thin, but maybe even a piece of sellotape would do.

I assume that there isn't any dust etc stopping the blade from seating correctly? I think that the easiest way would be to offset the blade a fraction- we are only talking half a mm, and I imagine that many people are running machines that are more inaccurate than that.

How do you mean that the table is no use as a datum surface- as a thicknesses, this is the datum?

 

[rosinante]

Hi the machine is an Inca 10 x 6 p/t, the infeed and outfeed tables are cast aluminium with steel wear jibs , these are adjustable and have in the past been "adjusted" I only use the machine as a thicknesser as I have a large cast iron surface, setting the blades was a pita , I have now engineered a steel reference plate that registers on the cutter head so with the use of a digital vernier blade setting is pretty accurate, to within 2 thou , mind you I have no idea of the repeatability, the thickness in bed again is a composite structure and being chain driven over 4 lead screws is prone to error, using a dti and raising the bed to mid position , zeroing the dti and checking each end I have a 20 thou ish error , I will have to off set the blades to minimise the error.
Agreed that the side to side taper is acceptable on wide boards as in general they are for making up table tops etc and accurate thickness is no so critical but in jointed frame members it is noticeable and requires extra work to level them ,
Thanks
Chris

 

[Myfordman]

Put a max width piece of mdf through to adopt whatever taper there is. Wax it thoroughly and use it as a false table for the thicknesser. a small batten tacked on the underside will stop it being dragged through with the work.

 

[Tealeaf]

Put a max width piece of mdf through to adopt whatever taper there is. Wax it thoroughly and use it as a false table for the thicknesser. a small batten tacked on the underside will stop it being dragged through with the work.

This idea I like!

 

[rosinante]

Well the mdf worked, I only had a bit about 180 mm wide put it through twice on same setting, reversed it fitted a cleat waxed it , less than 5 thou difference now on a piece of maple 120 mm wide , sorry about the mix of measurement units, can convert to gnats doodahs for purists, multiply the 180 etc by 40 ish to get that .
Thanks
Chris

 

[Fitzroy]

Didn't pitch in earlier, but wanted to say thanks to the OP and all whom replied. I've the same issue that I'd thought about posting a question on for a few weeks. Will go try the mdf trick myself now.

F.