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  #1  
Old Sat 05 July 2008, 10:01
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Taming a spider - how to get a flat base for the 6 rollers

A change of sequence - different to what is currently shown in the drawing set.

Drill holes for 6 V-rollers through the spider plate. Drill 8mm [5/16"] and leave out the tapping of threads shown on current drawings. The hole spacing is this dimension plus 11mm:



Screw Support Bushes M120220T to the spider with temporary screws and nuts at the back.

Weld the support bushes and the nuts to the spider plate:


After cooling, check spider for twist, by resting the support bushes on a flat surface. A tile, glass pane, counter top, table-saw top make a good reference for flatness. Here is a way to correct most of the twist that you may find. We call that green thing a crow bar - you may call it a wrecking or pry bar?:


Then file the tops of the support bases until the spider lays flat with all 6 bases in contact with the reference surface:

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  #2  
Old Sat 26 July 2008, 07:44
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
And then there was a really wild spider . . . plus a friend with a milling machine who owed me a favour . . . .

After welding the 6 support bases to the spider plate, laid the spider down on those bases. Only 3 were touching, shimmed the the rest to get the spider to lie firmly on the milling machine bed. Then skimmed the top edges of the feet (yellow arrows) for a reference, plus removed the major lumps off the side of the feet (red arrows).


Turned the spider over, laid it on parallel spacer blocks (to clear the z-motor lug), and then milled the 6 support bases to be flat in relation to each other:


This procedure is an overkill if one is only using 4 rollers, but the 6 roller version needs a precise alignment for the time when the slide enters and leaves the last set od rollers. That is, if your router is cutting at that time and you don't want to leave a mark in the work. It is more likely that one will not be cutting at that time, and that one is simply pulling the cutter up above the work.
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  #3  
Old Sat 26 July 2008, 09:50
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Let me be the first to ask.

Are those two blocks welded to the back for a air drill?
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  #4  
Old Sat 26 July 2008, 11:09
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
That's for the dust foot and hose mounting. Not tried yet, but I thought to weld it on just in case I needed it later. Our current dust foot "carrier" mounts off-center, to one side of the y-car, but that one hits the main table beams before the full y-travel is reached.
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  #5  
Old Tue 29 June 2010, 16:56
Zouave
Just call me: Eric #115
 
Sacramento, CA
United States of America
Just an idea... I have a granite surface plate. I was thinking about sticking a sheet of wet/dry sandpaper on it and using that for my final squaring of the 6 spacers. That should give me a really good planer area, right? Seems almost too easy...
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  #6  
Old Tue 29 June 2010, 18:16
David Bryant
Just call me: David #99
 
Western Australia
Australia
Hi Eric

This is what I have been doing yesterday. I am not really happy with it as the spider seams to flex under the hand pressure on the back of the spider. (but I only have a refference granite kitchen bench that I can use when SHE is out!).
I am not sure how accurate to make this or if I am being too picky so I look forward to hearing the answers as well.

Cheers

David
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  #7  
Old Thu 01 July 2010, 18:22
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
That method has been used by others. RobertM in Quebec used his jointer cast outfeed table as a reference surface if I remember right.
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  #8  
Old Sat 03 July 2010, 06:54
KenC
Just call me: Ken
 
Klang
Malaysia
Polished ceramic floor tiles make good reference surface too.
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  #9  
Old Mon 20 December 2010, 02:09
Red_boards
Just call me: Red #91
 
Melbourne
Australia
If you clamp the spider flat before welding and let it cool while clamped is this likely to reduce the heat induced distortion?
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  #10  
Old Mon 20 December 2010, 05:18
AuS MaDDoG
Just call me: Tony #71
 
Brisbane
Australia
Hi Red,

It may help having it clammped, but I do not think that will completely stop it.
Sanding all six bushes on a flat saw bench top will also take out any machining dsicrepencies.
To be honest it does not take that long to sand them all flat and at least you know the spider plate will sit true in the V wheels.

Cheers
Tony
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  #11  
Old Mon 20 December 2010, 06:25
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
A smart whack with a hammer after welding is the quickest way to remove most of the distortion, caused when welding the middle roller bases. I think we already mentioned how to take out twist?

Having something clamped across while welding will get in the way and won't eliminate all distortion because there will be "spring back" if there is a distortion problem.

Realise that the spider plate gets most of its stiffness after it is intalled in the y-car - there is a bolt/nut adjacent to each of the four outer rollers.
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  #12  
Old Mon 20 December 2010, 18:19
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Thanks Gerald and Tony
I read the crowbar technique and plan to sand things on a flat base, but I was hoping to minimise the twist to start with.
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  #13  
Old Sat 23 March 2013, 07:30
Hardouin
Just call me: Hardouin
 
Douarnenez
France
Hello !

I have a little problem with my spider. The slide tube is blocked by a spider protrusion :



Can you tell me what is this pin ?

Can I reduce it of 2mm with my grinder ?
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  #14  
Old Sat 23 March 2013, 10:37
xraydude
Just call me: Ted
 
New Orleans, LA
United States of America
That tab is designed to his the z-slide stop bolts. I am just going through this myself.

See this: http://www.mechmate.com/forums/showthread.php?t=226

Ted
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  #15  
Old Sat 23 March 2013, 12:10
Hardouin
Just call me: Hardouin
 
Douarnenez
France
Thank you Ted !
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