Zero Clearance Insert

[jdramsey]

Well, today was kinda cold and very rainy. Since I like to work out on the pad in front of the shop, I'll try tomorrow to cut the slot.

I did manage to start glue up on one of my projects tho, so it wasn't a total wasted day.

Brent

A local cable TV company has a show by WoodSmith Magazine. They just had a segment dealing with making your own Zero Clearance Insert. Pretty much the same discussion here. One thing they did, that I didn't think of, was they clamped a piece of plywood over the top of the insert before raising the saw blade. Their inserts just lay in the top of their powermatic table saw. It didn't occur to me because SS inserts are held in place by screws. In hindsight, clamping a piece of plywood might be a good safety feature the next time I make an insert.

[JPG]

A local cable TV company has a show by WoodSmith Magazine. They just had a segment dealing with making your own Zero Clearance Insert. Pretty much the same discussion here. One thing they did, that I didn't think of, was they clamped a piece of plywood over the top of the insert before raising the saw blade. Their inserts just lay in the top of their powermatic table saw. It didn't occur to me because SS inserts are held in place by screws. In hindsight, clamping a piece of plywood might be a good safety feature the next time I make an insert.

It would prevent flexing and tearout!

[charlese]

[quote="JPG40504"]My perception of NM does not include either cold or rainy!]

Perceptions of comfort vary by location(s). Here, it is cold if 50 degrees or less. Hot if it is 105 or more. Many days there is a 45 degree spread in temps. That's what we get with lower humidity. This time of year, the dew point hangs around 20 degrees.

When living in South TX, we had dew almost every morning - 365 day per year. My wife loved it! Said it was good for her hair and skin. I hated it! Couldn't stop sweating and had to fight rust all the time.

Just to keep on subject - 1/4" hardboard and some masking tape below works for me.

[tnerb]

[quote="JPG40504"]My perception of NM does not include either cold or rainy!]


Well, take today for instance. It started out overcast and about 45 degrees with no breeze. Late morning it had dropped to 30 degrees and started snowing. Lasted about 90 minutes, then the sun came out and it shot up to 55 degrees which is very warm in the sun here. The snow melted in about 15 minutes.

No wonder I have a cold.........

Brent

[JPG]

Well, take today for instance. It started out overcast and about 45 degrees with no breeze. Late morning it had dropped to 30 degrees and started snowing. Lasted about 90 minutes, then the sun came out and it shot up to 55 degrees which is very warm in the sun here. The snow melted in about 15 minutes.

No wonder I have a cold.........

Brent

Tomorrow, sleep in until after noon!:rolleyes:

[cincinnati10]

I made 3 today out of 1/4" MDF from HD that really wasn't 1/4" s.......
Brent

That's one of the beauties of Phenolic for jigs. Here's the characteristics:

1. It's exact dimensions. Zero-clearance insert requires no shimming.
2. It's dimensionally stable regardless of humidity.
3. It's hard, easily machinable, threads well. No tear-out on cutting the slot.

[dusty]

While it is true that phenolic that measures exactly 1/4" is available and it is also true that 1/4" hardboard measures less than that (about .237") - it is also true that the Shopsmith inserts do not measure .250".

I just measured six or seven of mine and they check in at anywhere from .237" to .243". All of my non-metallic Shopsmith inserts measure on the order of .237" to .240".

SO?

This means that unless you are using phenolic inserts and you absolutely need a flush fit you are going to have to use some sort of shim.

When is a flush fit absolutely necessary?

I have been using what I have (as stated above) for about twenty five years now and I don't recall ever having a problem that can be attributed to this sloppy fit. Maybe this is just because I don't fall into that category of "skilled, discriminating Shopsmith craftsman".

[honeywell]

I don't recall ever having a problem that can be attributed to this sloppy fit.

I agree. If the board spams the zero clarance insert than there should not be a problem. Now in the case of cutting a really thin strip. If it is going to hit the edge around the ZCI you might want to make it as accurate as possible. Does that make sense?

[JPG]

I agree. If the board spams the zero clarance insert than there should not be a problem. Now in the case of cutting a really thin strip. If it is going to hit the edge around the ZCI you might want to make it as accurate as possible. Does that make sense?

A long long time ago when I purchased my Goldie new, the inserts were slightly less than .250 intentionally. I assume they still are!

If I understand the 'original' thinking, one does want to eliminate the possibility of the insert being 'proud' on the front end(workpiece could snag on the insert). The inserts are curved with the middle of the bottom bulging outward. This allows setting the back flush to the table by slightly raising the rear screw(the front is screwed down tight). By allowing the back to raise to flush with the table, a workpiece will not snag on the table at the rear of the insert either.