Micro positioning device still at sears

[LCHIEN]

http://www.sears.com/shc/s/p_10153_12605_00922214000P

Sears shows 6 in stock at $26.99 sales price.

This is one of the best and little known BT3 accessories. Clamps to the front rail and can push of pull the rip fence block right or left - each turn is 1/16th inch and the knob is marked in 1/4 turns so you can easily position your rip fence by 1/64ths or better. Since the fence aligns when the lever is pushed down to the block position, this works great. Dead accurate. My only 2 caveats

1 watch backlash of a fraction of a turn when changing directions - try to only go one way or if you have to back up, go past the point and return to the set point in the original direction.
2. tightening the set screw, just a very light touch will do, the unlatched rip fence block is easy to move and doesn't require locking the Rapid Set hard at all, doing so will put dents in your front rail which is not bad, just cosmetically unpleasing.

This will fit any BT3 variant - BT3000, BT3100, sears 22811, 21829 etc.


Sears also showing wide table leg kit

http://www.sears.com/shc/s/p_10153_12605_00922219000P?prdNo=6&blockNo=6&blockType=G6

but that's not a must have, in my book.

[toolguy1000]

any application of this item to t-square fences, like a t-2? i couldn't find an owners manual @ sears.com.

[JimD]

This micropositioner is made to ride in a groove of the BT3000/3100 front rail and secure in position with a pin tightened against that rail. It is made to attach to the rip fence by you dropping the casting at the front of the rail over a hook on the microadjuster. It could work on another rip fence but you would have to figure out how to latch it to the rail and the rip fence.

To eliminate the slop and to make it easier to attach/detach the rip fence from the micropositioner, I epoxied a strong magnet with a steel base to the micropositioner and a small steel base to the rip fence. It works great. The magnet on the positioner is thick enough it projects just further than the hook. I think I got the pieces from Lee Valley. It is their smallest thin magnet.

I use this all the time. It is a major advantage of the BT3100. An example is cutting tenons. I made a jig that rides the rip fence. I do not normally make a check cut, I just nibble it away. Six marks on the micropositioner is reliably less movement than the blade will cut. When I get close, I may use less than one mark to get the fit very close. Minor difference in the thickness of the starting piece may mean I have to trim a little with the shoulder plane but the miropositioner gives me great accuracy. Even just cutting to width is easier with the micropositioner. You can rip a little wide, lock down the micropositioner and reliably move the fence to the exact position you need.

Jim

[LCHIEN]

The micro positioner is very BT3 specific. As JimD said, it rides in a t-slot on the BT3 front rail and its height is such that its below the table top and workpieces onthe table can glide over it without interference.

I usually measure rip widths with my digital calipers in inches and thousandths. Each marked turn of the knob is 62 thousandths so a quarter turn mark (and each mark is a different height so its easy to track and count them) is roughly .015. Its no sweat to actually place the knob in between marks so I can very easily dial something in better than .010 which is about the reaosnable limit of woodworking accuracy in my book.

so if my test rip measures 2.052" and I want to get it close to 2" then I'll move the rip fence .052 which is approx three and a half marks clockwise and usually I'll be within about .005 on the width, with a single adjustment and a second test cut. That's very good and you'l probably get about .005" variation in width alpong a rip anyway.

[pelligrini]

That's a cool idea on the magnets Jim. The only thing I don't like about the positioner is the slop in the hook and having to lift the fence to get it under. I use it a lot on my router fence (a second rip fence). I don't always leave it on. So, most of the times I really need it I have to lift the fence and mess up the setup I just did.

[LCHIEN]

... The only thing I don't like about the positioner is the slop in the hook and having to lift the fence to get it under. ....

funny, mine (on a BT3000) fits the fence block very snugly; maybe you should try some tape or something to shim it.

The magnet will sure ease the problem with slop and having to lift it off. Usually mine is unlocked and I just drag it around with rip fence. Unless i need the last 3 inches of rail travel...

[Chris_B]

To eliminate the slop and to make it easier to attach/detach the rip fence from the micropositioner, I epoxied a strong magnet with a steel base to the micropositioner and a small steel base to the rip fence. It works great. The magnet on the positioner is thick enough it projects just further than the hook.

This is a great idea! I'm going to steal it.

[Chris_B]

BTW, if you apply code "BTC5" (no quotes, valid through 8/27), the price drops a further $5 to $22.99 (+ $4.99 shipping).

I've dropped mine a few times so I decided to get a spare...

[LCHIEN]

only 2 left now.