Table Insert Mod Allows Micro Leveling

algale · Post by **algale** » Fri Nov 09, 2012 5:41 pm

For a while now my table (saw) insert for my 520 has bugged me. It has always sat too far below the table surface for my liking; for big work pieces it made no difference but for small or narrow workpieces there would be a noticeable drop as the piece moved off the table and over the insert.

Today I finally decided to do something about it. I drilled and tapped holes for 4 stainless steel Allen-head set screws 10-24 x 1/4 inch. The photos tell the story. Now I can very precisely level the insert with the table top.

[ATTACH]19006[/ATTACH]

[ATTACH]19007[/ATTACH]

[ATTACH]19008[/ATTACH]

[ATTACH]19009[/ATTACH]

[ATTACH]19010[/ATTACH]

hb2 · Post by **hb2** » Fri Nov 09, 2012 6:12 pm

That is good engineering - simple and effective

JPG · Post by **JPG** » Fri Nov 09, 2012 9:42 pm

From a gander at your pix, I would suggest using 5/16" set screws. If slightly too long, grind the point down enough to assure the top is not proud.

That would place more thread turns in the insert.

FWIW, 10-32 screws would be 'finer'!

dusty · Post by **dusty** » Sat Nov 10, 2012 6:11 am

I think you have done! I often wondered why Shopsmith had not done something like this.

I have almost quit using the Shopsmith inserts in favor of my own partially for this reason.

algale · Post by **algale** » Sat Nov 10, 2012 7:18 am

JPG40504 wrote:From a gander at your pix, I would suggest using 5/16" set screws. If slightly too long, grind the point down enough to assure the top is not proud.

That would place more thread turns in the insert.

FWIW, 10-32 screws would be 'finer'!

I see your point in this thread.

As installed, the set screws don't need to extend as far out as in the photos showing the back of the insert, which were taken before I leveled the insert. So, in operation, there's more thread in the insert than the photos suggest.

The insert is 0.250 thick (give or take a few thousandths) and sat about 0.007-0.008 too low. So I think a 5/16ths set screw would definitely be too long and would sit proud. And after grinding the point down, there would be a negligible amount of additional thread remaining in the insert (assuming the use of the same thread pitch).

On the other hand, using 10-32 x 1/4 set screw definitely would put more threads in the insert and would have been a good idea had I thought of it.

I may try to make a few ZCI's that incorporate set screw levelers but I don't know how well wood/plywood/hardboard will take the threads. If I am successful I will post the results.

dusty · Post by **dusty** » Sat Nov 10, 2012 7:56 am

algale wrote:I see your point in this thread.

As installed, the set screws don't need to extend as far out as in the photos showing the back of the insert, which were taken before I leveled the insert. So, in operation, there's more thread in the insert than the photos suggest.

The insert is 0.250 thick (give or take a few thousandths) and sat about 0.007-0.008 too low. So I think a 5/16ths set screw would definitely be too long and would sit proud. And after grinding the point down, there would be a negligible amount of additional thread remaining in the insert (assuming the use of the same thread pitch).

On the other hand, using 10-32 x 1/4 set screw definitely would put more threads in the insert and would have been a good idea had I thought of it.

I may try to make a few ZCI's that incorporate set screw levelers but I don't know how well wood/plywood/hardboard will take the threads. If I am successful I will post the results.

Based on my experience with 1/4" hardboard, it is a tad bit thin. I use one thickness of black duct tape on the bottom side of the ZCI.

I can't tell you in thousandths of an inch how it fits but it works for me. I used to put the tape on the table but the surface area was to small to be reliable. Now I just add the tape to the ZCI.

pennview · Post by **pennview** » Sat Nov 10, 2012 8:57 am

To strengthen the threads in wood, plywood, hardboard, etc., use some thin CA (super glue) on the threads. After it dries, add another coat or two, and then clean up the threads with the tap and you should get some solid threads in those materials.

JPG · Post by **JPG** » Sat Nov 10, 2012 9:06 am

Hard close grained hardwoods will tap well. Some thin CA will 'harden' the threads.

The outer flange where the threads are is about 0.135 which allows about 3 1/4 threads at 24 tpi and about 4 1/3 threads at 32 tpi.

The 510 table that I have varies in depth to the surfaces that the insert 'nubbins' press against. When installed, the insert sits about 0.015 below the table top surface. I assume that is intentional so that workpieces will not snag on the insert.

Perhaps smaller workpieces should be 'sawed' on the scroll or bandsaw which already have adjustable insert height adjustment;).

I think shimming at the retaining screws and four of these screws located between the 'nubbins' about 4 1/4" from the front screw, and about 4 1/2" from the rear screw on each side would work well.(puts the screws mid point between and in line with the 'nubbins')

If we wanted to really get carried away, the table can be tapped!:rolleyes:
(ala 10 E/ER)

Ed in Tampa · Post by **Ed in Tampa** » Sat Nov 10, 2012 10:34 am

I have never had a problem leveling my inserts to my table. All my SS inserts have a slight bend in them (I think Shopsmith calls it "coining") so when the back is tighten down the front of the insert is proud of the table about 1/8" or so. I then tighten the front hold down screw down until the insert is level with the table.

algale · Post by **algale** » Sat Nov 10, 2012 10:56 am

[quote="JPG40504"]Hard close grained hardwoods will tap well. Some thin CA will 'harden' the threads.

The outer flange where the threads are is about 0.135 which allows about 3 1/4 threads at 24 tpi and about 4 1/3 threads at 32 tpi.

The 510 table that I have varies in depth to the surfaces that the insert 'nubbins' press against. When installed, the insert sits about 0.015 below the table top surface. I assume that is intentional so that workpieces will not snag on the insert.

Perhaps smaller workpieces should be 'sawed' on the scroll or bandsaw which already have adjustable insert height adjustment]

You definitely want to be very sure when you install and level the insert that the work piece won't snag. But 0.015 is overkill, IMHO.

Once you install these, I think you will find that you won't need to shim at the front and back center factory screws. I am getting very good front to back and side to side leveling with the new set screws and the factory screws at the front and back center can be used to get additional adjustment at the front and back center without any shimming.

I will admit that my placement was a bit of guess work, but seems to have been a good guess.