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  #1  
Old Mon 08 February 2010, 21:12
blakekoehn
Just call me: Blake #47
 
Macon, MS
United States of America
Post copied from elsewhere:

. . . so I could surface the table. . . . .

http://www.youtube.com/watch?v=RL3M0n5sRLM
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  #2  
Old Mon 08 February 2010, 21:32
rayditutto
Just call me: Robin
 
Victoria
Canada
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just saw the surfacing video - i'm wondering about the ridges on the surfaced portion - does anyone have an idea why they appear?

cheers
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  #3  
Old Mon 08 February 2010, 21:53
lumberjack_jeff
Just call me: Jeff #31
 
Montesano, WA
United States of America
Two things. Often stripes are because the cutting face isn't absolutely parallel with the plane of travel.

Also because (like a lawnmower) the tool pushes the fibers of the mdf one direction on the left side of the cutting path, and the other direction on the right side of the cutting path.
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  #4  
Old Mon 08 February 2010, 22:46
rayditutto
Just call me: Robin
 
Victoria
Canada
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Jeff,

sounds plausible - i had thought of the first but not the second

it seems to me that the cutting face might not be parallel with the plane of travel for a couple of reasons . . .
1) the Z plate is not perpendicular to the X & Y axis'
2) the longitudinal axis of the router is not parallel to the Z axis (plate)
3) a combination of 1 & 2

it seems that by shimming the router in the clamps it should be possible to arrange for the cutting face to be parallel with the plane of travel (with the possibility of translation in the X-Y plane as Z rises & falls)

the thread on squaring the Y axis with the X axis is excellent - is there an equivalent for getting Z plumb with X-Y?

it feels like i may be hi-jacking Blakes thread here so if this belongs elsewhere . . . pls give it a new home
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  #5  
Old Tue 09 February 2010, 01:04
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Robin, in my SB days there was a big argument about this. (one of the posters in that thread lost his cool, had his angry post removed and refused to come back to the forum until I left.)

There are basically two things to check for for squareness, and they are done in the following sequence:

However, you first need to create a reference table surface to take the measurements from. Do a surface cutting procedure on a small part of the table (or on scrap firmly fastened to the table) while the y-car is in the middle of the gantry (minimises effects of a possibly twisted gantry). Lay a pane of glass on that area.

First squaring procedure: Make sure that the z-slide movement is sqare to the table. This assumes that you have already set your eccentrics and don't want to re-adjust them, thus all the adjustment is done on the 4 screws holding the spider to the y-car. Use a framing square up from the glass pane and get the z-slide plate running square by adjusting shims/slots at the 4 screws of the spider mounting. Check in x and y direction. It is easier to do this before mounting the router/spindle. Just get the z-slide square to the table. You could tweak the eccentrics for squareness in the y-direction. (you can also hold the square against the rollers, instead of the actual slide)

Second squaring procedure is to get the router/spindle's rotational axis square to the table. A trammel is used for this. If you have good precision brackets, you shouldn't need any adjustment on the brackets. One can go super precise with dial-gauge trammel.

A simple trammel with a 1/4" bent rod soldered into a piece of precision 1/2" round bar, scribing a radius of around 6" is enough. You can use a feeler gauge under the tip for real accuracy, but we generally just check that it scribes with equal pressure all the way around.




Of course, you must unplug the router before you mount the trammel . . . .
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  #6  
Old Tue 09 February 2010, 06:48
normand blais
Just call me: Normand
 
montreal
Canada
You was so young back then Gerald
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  #7  
Old Tue 09 February 2010, 06:56
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
!
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  #8  
Old Thu 11 February 2010, 09:39
rayditutto
Just call me: Robin
 
Victoria
Canada
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i've tried a small mod to the process described - with an auto Z setter you can rotate the trammel by hand through each quadrant and run Z down to the touch plate - the DRO in Mach will give you your measurements
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  #9  
Old Thu 11 February 2010, 11:33
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Gerald,

thanks for that tip about the trammel.
We did this procedure yesterday and indeed. After surfacing the table we got a much better surface then before we used the trammel method. Our z-slide is square to the table.

Ries
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  #10  
Old Thu 11 February 2010, 12:00
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
You could also swing a dial gauge on router trammel:



But realise that your trammel has a much bigger swing radius than your cutter's tips and so the error effect in reality is much less than you see with the trammel.

(The sketch above is from the ancient way of lining up motors and gearboxes - same principles apply)
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  #11  
Old Thu 11 February 2010, 16:08
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Gerald,

That the swing of the trammel is bigger is exactly what's needed at that point. When we where facing the table we did notice that nice cut pattern, and that reminded me directly to this thread so much to learn... so much to learn

Ries
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