I just got two nice new solid-surface cast-iron table saw extensions
to replace the webbed ones that came with my old Craftsman table saw.
The old webbed extensions had holes on either end but the new ones
have holes on only one end.
I would like to still use the old webbed extensions to further extend
the new extensions but to do so it seems like I would need to drill
4 oversize 5/16" screw holes (oversized to allow fine adjustment) to
line up with the holes on the webbed extension.
The holes would have to go throuh about 3/8" of cast iron.
How hard would it be to drill such holes?
- Any special bits?
- Or should I take this to a machine shop or something to get it done?
Cast iron drills easily enough - nothing special needed except maybe a bit
of oil or some WD40 to lubricate the bit. Drill a pilot hole first which
will keep you larger bit from wandering.
Can't say I'm crazy about your idea of attaching the solid extensions to the
web extensions but maybe the other way around would be better. Use the
lighter web extensions furthest out and make sure to use some big washers on
the bolts that hold the extensions together. Be sure you have some metal
shimming material so when you assemble the extensions, you can shim them so
the top surfaces are flat across and in alignment with the main table.
You didn't mention how wide or heavy these extensions are but consider that
you may have to add bracing to prevent warping of the extensions over time
or breaking the cast iron edges because of to much stress.
A few years ago I added a router wing to my contractor saw outboard of the
pre-existing webbed wing (although it was designed to be a replacement wing; not
an additional one. I ended up building an additional outboard wing for the
other side of the saw out of oak and melamine to better balance the load and to
increase the saw's ability to handle sheet goods. I have had no problems with
warpage or sagging since then and have not added bracing.
Drilling holes was pretty much a non-event. Just be sure to do it in places
that leave you room to get a wrench around both the bolt head and the nut so you
can tighten the hell out of it as required.
I guess I was unclear -- I was planning on mounting the lighter web
extensions to the inner solid extensions (both from a weight/balance
perspective and because I want the nice smooth solid surface
extensions closer to the blade which in fact is the primary reason
that I bought the solid extensions to replace the old web ones).
Second, I shouldn't need to use shims if I use the same size holes as
in the original extensions since they leave enough room to move the
extensions up/down to align the surfaces..
The extensions are each 24" wide. I was planning on adding legs at the
far ends either made of 2x4's or angle iron.
Thanks for the comments and feedback!!!! Much appreciated.
If I'm understanding correctly, shims generally aren't for vertical
(up/down) alignment. They are used to correct angular misalignment.
For example, after bolt-up, you find the outside edges of the
extension are lower than the inside (bolt side) edge so that the
extension slopes downward. Shims on the lower side of the adjoining
surface, below the bolts, will kick the outer edges up so that the
extension is co-planar with the table.
No problem drilling in cast iron.
1) center punch - with regular bits,
2) drill small pilot hole (approx 1/8")
3) drill larger hole.
I use "cutting oil" (normally for cutting pipe threads and readily
available) for a lubricant when drilling iron or steel.
That's all there is to it.
Not hard to do. Centerpunch and pilot with a small diameter or use one
of the "Pilot Point" bits I've seen from DeWalt. Best to use a cutting
oil for lube and cooling. I usually use the same cutting oil sold for
cutting pipe threads. Drill at a much slower RPM than you'd use for
wood. If you can jig it up to a drill press, that'd be my choice.
Not really except the brad point bits used for wood would be a poor
choice. There are two general "standard" twist bits, those with tips
ground at 118* and others at 135*. 118* are very common and should
work fine. If you have 135* bits, they may work better in cast iron,
but if you don't have them, it wouldn't be worth going out of your way
to get bits with the shallower angle for no more than you're talking
You could do that, but it's simple enough to do yourself.
The only thing I can add to other's remarks is to be cautious as the
drill bit starts to break thru, If you are using a powerful 1/2"
drill by hand the bit can grab when you least likely expect it to as
it breaks thru. Leave the trigger lock off when it gets close.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.