LumberJocks

Sealing table saw sleds and other jigs to prevent warping from moisture

  • Advertise with us

« back to Jigs & Fixtures forum

Forum topic by Rick1970 posted 02-09-2015 04:24 PM 1388 views 0 times favorited 15 replies Add to Favorites Watch
View Rick1970's profile

Rick1970

8 posts in 673 days


02-09-2015 04:24 PM

For those of you who live in humid climates, do you seal, (apply some kind of finish) your sleds and jigs? Even those made from plywood. Here in Alabama, where I live, I find it difficult to find a straight piece of plywood. Granted, I haven’t tried any of the lumber yards yet, just the big box stores.

I recently made a table saw sled and it warped slightly, not very much but enough to push my cuts out of 90 degrees. Would sealing with, say, shellac have prevented this?

-- I'd rather be making sawdust.


15 replies so far

View Ghidrah's profile

Ghidrah

667 posts in 682 days


#1 posted 02-09-2015 06:24 PM

I keep a dehumidifier running most of the yr, once the shop temp drops below 45° I shut it down. In general if laminating the rule of thumb is to dupe the mat on both sides. If you only have 1/2”, 5/8 or 3/4” ply as your platform it shouldn’t be a problem unless you’re using a low grade ply like CDX meant for exterior sheathing. Cabinet grade, AC or Luan, Most of jig platforms are 1/2 Luan.

-- I meant to do that!

View agallant's profile

agallant

530 posts in 2346 days


#2 posted 02-09-2015 07:15 PM

I live in NC and the only time my shop is climate controlled is when I am in there, scratch that I have become accustom to the weather down here and have stopped turning on the AC in the shop. I have never had a sled or jig warp.

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#3 posted 02-09-2015 07:26 PM

I use baltic birch for all my jigs/sleds. They stay unfinished, and I’ve not had one warp yet. Finishing will slow the moisture penetration somewhat, but it won’t stop it. You have to finish all sides, and that might make thing slide with more resistance over cast iron. We likely don’t have your humidity, but that’s not to say we don’t have any….it gets pretty damp around here at times in the summer.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Ghidrah's profile

Ghidrah

667 posts in 682 days


#4 posted 02-09-2015 07:53 PM

I don’t treat my platforms either. High summer I empty my dehumidifier 3 times a day, the bucket trips at about 2 1/4 gals. 2 yrs back, (#2) the old one died in early summer didn’t realize it till the tables began to discolor, by the time (#3) was up and running I had to resurface 6 tables, hadn’t had to do that in over 15 yrs.

-- I meant to do that!

View Bill White's profile

Bill White

4448 posts in 3420 days


#5 posted 02-09-2015 08:17 PM

I make it a habit to seal all my jigs with a coat of shellac ( maybe 2 or 3 depending), then waxing with Johnson’s Paste Wax. Just a habit to make all the jigs, etc. smooth and easily super slick to what ever top they might encounter.
Does this mean that I’m habitual? :)
Bill

-- bill@magraphics.us

View Ghidrah's profile

Ghidrah

667 posts in 682 days


#6 posted 02-09-2015 11:04 PM

MDO works well too.

-- I meant to do that!

View Rick1970's profile

Rick1970

8 posts in 673 days


#7 posted 02-10-2015 01:43 AM



I keep a dehumidifier running most of the yr, once the shop temp drops below 45° I shut it down.
- Ghidrah

I had not thought of using a dehumidifier; I’ll have to try that as spring is right around the corner.

-- I'd rather be making sawdust.

View Rick1970's profile

Rick1970

8 posts in 673 days


#8 posted 02-10-2015 01:53 AM



I make it a habit to seal all my jigs with a coat of shellac ( maybe 2 or 3 depending), then waxing with Johnson s Paste Wax. Just a habit to make all the jigs, etc. smooth and easily super slick to what ever top they might encounter.
Does this mean that I m habitual? :)
Bill

- Bill White

Yes in fact you are habitual, but in a good way.

-- I'd rather be making sawdust.

View Rick1970's profile

Rick1970

8 posts in 673 days


#9 posted 02-10-2015 01:57 AM

Thank you for the responses. It would seem I just did a poor job of building my sled. the base is 1/2” birch but the fence is two laminated pieces of 3/4” CDX. I need to stop being cheep and use the proper materials. However I don’t think I’m ready to use hard wood for jigs. Just can’t bring myself to do that yet.

-- I'd rather be making sawdust.

View rwe2156's profile

rwe2156

2187 posts in 940 days


#10 posted 03-05-2015 02:10 PM

From the humid south:

I’ve found MDF for your sleds works well.
Coat it with BLO and shellac it.

Store sled vertically.

No problems

-- Everything is a prototype thats why its one of a kind!!

View TheFridge's profile

TheFridge

5764 posts in 945 days


#11 posted 03-05-2015 02:40 PM

You can get good birch or other generic hardwood ply from the box stores that is useable, but you just have to dig a little bit. I use 2-3 laminated pieces of ply for the fence. Pretty much eliminates warping and is easy to make.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Rick  Dennington's profile

Rick Dennington

5170 posts in 2654 days


#12 posted 03-05-2015 03:49 PM

All my jigs, fixtures, and sleds are finished with 2-3 coats of Tung oil….When completely dry, a coat of Johnsons.

-- At my age, an "all--nighter" is not having to get up and pee...!!!

View DrDirt's profile

DrDirt

4167 posts in 3202 days


#13 posted 03-05-2015 05:20 PM

I had a crosscut sled made from baltic birch and it warped. Not bad enough to mess up the 90 degree cut, but it made a hump on the right side, such that there was a lip at the saw kerf that prevented sliding stock smoothly from left to right.

I made a new sled from MDF, and because i was concerned that it could get set on a wet spot, and soak up some water, I sealed it I just had a partial quart of bullseye Seal coat shellac

-- 'Political correctness is fascism pretending to be manners' ~George Carlin

View OSU55's profile

OSU55

1056 posts in 1449 days


#14 posted 03-06-2015 05:22 PM

I seal all of my jigs/fixtures with shellac, not for preventing warping per se, but to prevent any liquid that may be spilled from being absorbed. Glue is easily removed from a shellac surface, but not bare wood. Saw dust or other dust/dirt will slide right off, but not off bare wood. My sometimes oily/greasy hands won’t stain a shellac surface, etc. Just too easy to throw on a coat of shellac and know I don’t have to worry about all the possible things that can cause problems with bare wood.

View sawdustjunkie's profile

sawdustjunkie

343 posts in 1177 days


#15 posted 03-06-2015 06:39 PM

I also made a sled with Baltic Birch 1/2” and the right side warped by almost a 1/2”.
I tried to cut the rear back stop and put some weight on it to see if it will flatten out.
If it doesn’t, I’ll make a new one with MDF. I have other jigs using that and have never had any of the warp.
What suprised me is the Baltic Birch actually warped that much.
My shop is the garage and I have heat in the winter, but no humidity control at all for the summer.

-- Steve: Franklin, WI

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com