Any advice on widening miter slots?

[BrazosJake]

I bought an old Emerson-built craftsman contractors saw off of Craigslist, sans miter gauge. Yesterday, a brand-spanking-new Jessem gauge pops up on CL, too cheap to resist (it's now mine). One problem: My Craftsman miter slots are a hair too small, the measure a shade under .74, while the Jessem bar is right at, or a hair over, .74 (my old RCBS calipers only go to 1/100").

I'm thinking of making a simple lap from plywood and SC sandpaper to hone the sides of the slots a bit, or maybe even valve-grinding paste.

Any ideas?

This is such a nice gauge, I think it will be worth the effort.

[messmaker]

My first thought would be a router and stone with a 1/4 shaft.You could use the tablesaw fence as a straight edge. The speed of the router would concern me though

[cgallery]

Although it wouldn't seem like it, it is going to be painful to remove precisely .002" from the wall of your slot. Especially w/ sandpaper. I would google it a little and see if other users have figured out a way to expand their miter slots. Or, have the miter bar machined to make it fit. Or contact Jessem and see if they will swap one for you (if they have them).

[Imadunatic]

is there a machine shop close by?? or do you know a guy who knows a guy that works at a tool and die or machine shop?? i wouldn't guess an old fashioned machine shop wouldn't hit you for much more then 10 bux for milling one side of the slot, who knows tho, feel free to send it to me and I'll mill it for you, shipping to michigan might be a little steep tho :-(

Kevin

EDIT: I know you're miter guage is brand spanking new, but it might be easiear to machine that to fit, rather then widening the slot, only trouble is if you upgrade table saws, then your miter guage is sloppy, and nobody likes that!!

[BrazosJake]

Although it wouldn't seem like it, it is going to be painful to remove precisely .002" from the wall of your slot. Especially w/ sandpaper. I would google it a little and see if other users have figured out a way to expand their miter slots. Or, have the miter bar machined to make it fit. Or contact Jessem and see if they will swap one for you (if they have them).

I won't have to be too precise, the miter gauge bar does have some width adjustment.

Another option, which I saw on Sawmillcreek sometime back, was where someone with and old Cman saw actually went to work with a circular saw, abrasive wheel, and straightedge and milled out a big enought slot to epoxy an incra miter slot in place. So I guess if I screw it up I could do that.

[tfm37]

miter slot

The saw table is cast iron. Cast iron is easy to scrape. Heres how. Get an old file. Grind all the teeth off of about two or three inches of the end. Grind the end of the file at 90 degs with a slight radius. Hone this edge on a fine stone.
To use , hold the scraper at about 45 deg on one side of the slot and scrape off the metal. Be consistant and work your way from end to end, always scraping on the same side. Test with your miter bar frequently. Don't touch the other side of the slot, its your reference to maintain the two sides parallel. It shouldn't take over 30 minutes per slot.

[cabinetman]

I would first check the top edges of the slot to see if they are slightly peened inward toward the slot. After a lot of use or abuse, the edges of the slot could have been (banged) inward. Lay a straightedge across the slot to see if the edges are lower than the table. If you want to "clean" up the edges of the slot, use a sharpening stone along the edge uniformally, or an 80 grit or 100 grit silicon carbide sandpaper, used wet (the grey wet-or-dry) paper on a straight block.

Then if the miter gauge bar still doesn't fit, it may be easier to take a smidgen off one edge.

[softop41]

Brazos,
It's gonna be a lot easier to make the gage fit the slot than vise-versa. If it was me, I'd narrow the miter gage bar since it has compensation adjustment. For the amount indicated, draw filing carefully would do the trick and then adjust it to the slot.
YMMV,
Jerry

[BrazosJake]

Brazos,
It's gonna be a lot easier to make the gage fit the slot than vise-versa. If it was me, I'd narrow the miter gage bar since it has compensation adjustment. For the amount indicated, draw filing carefully would do the trick and then adjust it to the slot.
YMMV,
Jerry

For those not familiar with this gauge, it retails new for quite a bit more than I paid for the saw. If I ever upgrade TS, I'll want to keep it, so altering the gauge bar is not an option. Attempting to narrow it would likely ruin the width adjustment.

Besides all that, the gauge bar is steel, vs cast iron for the saw top, so I doubt it would be easier.

I thought about selling it and going to an Incra 1000SE, but Incra's email reply says standard slots only, so I may as well make this one fit.

[tfm37]

This site gives a good explanation of the metal scraping process.

http://en.wikipedia.org/wiki/Hand_scraper

[BrazosJake]

OK, found a picture of a hand scraper made from a file here:

http://www.practicalmachinist.com/cg...;f=12;t=001327

Are you saying the convex end would comprise the cutting edge? If so, seems like it would be awfully hard to scrape the side of the slot flat, get a clean corner where it meets the bottom.

[tfm37]

The convex end is the cutting edge. It is ground square with the slight radius and then honed. It will remove cast iron very quick. You can scrape parallel to the groove and then perpendicular to reach the bottom. Do the scraping on only one side. You will be working on only a short section at any time. Use the miter bar as a gage and check your work frequently. If you start at one end and work on the first inch till the miter bar will enter, then move to the next inch and repeat. You will probably find there are high and low spots.Just be sure to do all your work on one side. I am assuming the sides are parallel.

[BrazosJake]

I owe ya one, TFM, that worked like a champ. It took very little scraping to get the gauge to fit.

For future reference, an HSS round nose scraper designed for a turning wood makes an excellent cast-iron scraper.