Spider Plate Oh-Oh!! (which # mark to drill on?)
 

Just thought I'd pass on a note to those that are not to the point of welding on the nuts to the spider plate yet. According to the DXF drawings, and the spider plate from Alabama Joe, there are three laser marks you can choose from to center your drill bit on at each nut welding point. If you are planning on using the 4" wide Z plate, I would strongly suggest using the outer hash marks. I was a bit confused as to which to use, so instead of asking the forum (didn't want to look dumb!!!) I just chose the center hash marks to drill on. Big mistake. Lesson learned, if in doubt it's better to appear dumb and get the right answer rather than prove you really are dumb....


SteveE

The choice of mark to drill on is dependent on a couple of variables . . . .
- metric or inch slide plate
- bend radius of your bending company
- and a few more.

The idea behind the "hash" marks is to give a general, but not exact, location.

Steve,

I also found that the hash marks are not truly parallel with the mounting ears. So it pays to check the dimensions. Of course you can make adjustments with the eccentric bolts, but it's possible to drill the holes out of the range of the eccentrics.

Thank you for sharing your experience.

Regards,
John

Somewhere on this forum is a picture of measuring the spacing between the v-rollers for the spider plate. But I can't find it. (Don't laugh JR!)

:D

http://www.mechmate.com/forums/showthread.php?t=1098

something similar I think to find the actual centres.

Thanks Irfan! That one pointed me to the first post in this thread which said:

The hole spacing is this dimension . . . . . . (plus more - see below photo)


. . . . . .plus 11 millimeters

The caliper is holding the 12mm ID rollers tight against the slide. The difference between the 11 and the 12 is 1mm adjustable for preloading on the eccentrics.

I didn't want to appear dumb either
 

I used the outer hash marks, and even then, only 4 rollers fit. Is it better to machine the slide, buy another spider, or weld close and redrill the spider holes?

It very much depends on your welding skills. There is no loss in trying to weld up and re-drill, except time.

...oh, I drilled and welded, and drilled again. No harm....just be careful to not get to hot and warp the plate. I chose to plug weld from both sides with a backer plate to try keep the shrinkage to both sides of the plate.

Mine worked out just fine.

Sean

A good backer plate for plug welding a hole is either aluminium or copper - steel welding doesn't stick to it and they conduct away heat.

A piece of used copper buss bar from an electrical panel works well, :) dont ask how I know.

Revisiting this issue
Using a 100mm plate and size 3 bearings (diameter to bottom of vee is 20mm), then the space between the hole centres on the z-plate needs to be ~140mm (and the ~132mm on plan 10 40 430 W is very approximate).
So drill the outside marks, not the centre ones.
Or am I missing something?

The marks on the plate are delibrately confusing......so that you do not use the marks for drilling. Only use the marks for centering your own marking out, after you have found the correct spacing as per picture above plus 11 mm.