Shopsmith Forums

Mike907 wrote:I cleaned the residual packing lubricant from the tapered arbor and the chuck bore and drilled holes up to 1 inch diameter. The chuck stayed on the arbor just fine. Its is also very easy to open to change bits. Time will tell if it grips as well as a keyed chuck. I wasn't able to test for runout, but the test holes all seemed smooth, round, and straight.

Here is a comparison shot confirming what Dusty said. You lose 2.4 inches of drilling room.

[ATTACH]20995[/ATTACH]

I finally found my original chuck so that I could take this picture, now if I could only find the key.

Mike

You can send me the chuck, it doesn't sound like you use it much.

Maybe you can send me your spare key, then I can use it more.

Mike

Send the old 1/2 inch chuck to me please. I lost mine!!! I'll find a key.

Sorry it took so long to report (from the last thread on this).
I got the new chuck and have used it for a variety of things thus far- some easy, some almost abusive.
Not one problem.
The lock occurs in a twitch. From contact with the bit to full solid lock is a mere thought. Adjusting the chuck to hold a bit is done with one hand (and soooo smooth) as the rest of the power train offers just enough resistance to keep the shaft from turning til you get to locking position. And unlock is unbelievably easy as well.
Yes, the body is big and heavy and knurly, the better to get most of your hand on, with a no-slip grip, to feel good about your locking it. And with the jaws opening at 1/12" per revo the adjustment is finessed but sure and solid.

Dug a bunch of 1" and 7/8" holes in 3/4 and 1-1/2 PT Doug Fir with various grain orientations and had not a glitch at all. Granted the use of SS BradPoint bits made the job easier rather than harder, and cleaner, but there wasn't a hint of wobble, strain, protest or tearing {or grabbing the workpiece}, and PT DF is miserable stuff to poke clean holes in ordinarily.

I love this thing. (I may have mentioned this before, but before a lot of these holes confirmed it.)

One surprise was to see the JT3 adapter featured here. I didn't even realize there was an adapter in the assembly! (That's how eager I was to put this baby to work!) It's held on by a smaller than SS-std allen screw lodged in the grip ring, which I also missed.
As I look at this thing now I see- I think- another curiosity, and I guess I'm going to have to investigate it and the ring screw. The (SS)std (5/32) allen screw that locks the adaptor to the arbor is not angled to match the arbor sloped flat (eyeballing it, but I'm pretty sure). Its hole appears to be drilled perfectly perpendicular to the shaft.

Now where have I seen or read about this peculiarity in another device lately?

I can't imagine this is a concern, considering the uses (and forces) to which this unit should be put.

trainguytom wrote:Every keyless chuck I've ever used seems to slip under all but the lightest drilling procedures. I've got a pretty strong grip, but nothing like what a keyed chuck system offers.
...

There is obviously some other kind of mechanism at work here, since getting full lock on a bit involves very little torque or 'grip'. I bet I could get this thing to lock using only fingertips (and maybe just two!).

There's some genius at work here, the likes of which I've never encountered befo.

"It's held on by a smaller than SS-std allen screw lodged in the grip ring"

I might be mistaken, but I think that the allen screw only holds the knurled ring to the chuck and doesn't go through to the JT3. I can't confirm this now, since my chuck and the adapter aren't coming apart without some marring inducing force. There is no hole through the chuck to knock out the taper like there is with a lathe.

Mike

Mike907 wrote:"It's held on by a smaller than SS-std allen screw lodged in the grip ring"

I might be mistaken, but I think that the allen screw only holds the knurled ring to the chuck and doesn't go through to the JT3. I can't confirm this now, since my chuck and the adapter aren't coming apart without some marring inducing force. There is no hole through the chuck to knock out the taper like there is with a lathe.Mike

You may be right. I also notice upon further investigation that the "smaller than SS-std allen screw" that I called out is not, after all, an allen, but rather one of those "star" type screws, that are sometimes used when high torque is called for.
But I am now in "if it aint broke don't fix it" mode, so I'll not be looking into it any more unless it comes apart by itsownself.

Something new- boring some more holes in PT Doug Fir and hit one particularly tough spot. Momentary "grab" as the bit hit the spot then drove on thru it. When removing the bit afterwards, noticed that it was significantly more difficult unlocking the chuck. Not difficult, mind you, but "more difficult" than the normal ridiculously easy that I expect.

keakap wrote:You may be right. I also notice upon further investigation that the "smaller than SS-std allen screw" that I called out is not, after all, an allen, but rather one of those "star" type screws, that are sometimes used when high torque is called for.
But I am now in "if it aint broke don't fix it" mode, so I'll not be looking into it any more unless it comes apart by itsownself.

Something new- boring some more holes in PT Doug Fir and hit one particularly tough spot. Momentary "grab" as the bit hit the spot then drove on thru it. When removing the bit afterwards, noticed that it was significantly more difficult unlocking the chuck. Not difficult, mind you, but "more difficult" than the normal ridiculously easy that I expect.

And when removed, what did the bit shank look like? Was it round and scarred, or multi - flatted?

I be curious if the momentary grab was slipping on the shank or 'self tightening' the chuck.

JPG40504 wrote:And when removed, what did the bit shank look like? Was it round and scarred, or multi - flatted?

I be curious if the momentary grab was slipping on the shank or 'self tightening' the chuck.

Very good question. The visual of the momentary grab (for lack of a better term) was that the bit appeared to stop for 2 or 3 milliseconds (as if under a strobe light), and for all I know it did (the powpro is capable I guess), before powering thru the problem spot. I too wondered about the bit shaft, and was very pleased to see that even under bright lighted magnification it had zero evidence of anything unusual (no sign of slippage). I hadn't thought of it the way you put it, but now I'll consider that pause (sts) to have been the chuck 'self-tightening', and done quickly enough to prevent damage.

And I just realized (remembered) that in the past I have had bits damaged in exactly that way- shaft damage-, in the old standard original-equipment SS chuck, tho I will not rule out possible causes being not having tightened the chuck properly (using all 3 holes), or pushing the equipment beyond reasonable limits.

keakap wrote:Very good question. The visual of the momentary grab (for lack of a better term) was that the bit appeared to stop for 2 or 3 milliseconds (as if under a strobe light), and for all I know it did (the powpro is capable I guess), before powering thru the problem spot. I too wondered about the bit shaft, and was very pleased to see that even under bright lighted magnification it had zero evidence of anything unusual (no sign of slippage). I hadn't thought of it the way you put it, but now I'll consider that pause (sts) to have been the chuck 'self-tightening', and done quickly enough to prevent damage.

And I just realized (remembered) that in the past I have had bits damaged in exactly that way- shaft damage-, in the old standard original-equipment SS chuck, tho I will not rule out possible causes being not having tightened the chuck properly (using all 3 holes), or pushing the equipment beyond reasonable limits.

Good news indeed! So the shaft was 'round', not hex or triple or other multi-faceted genre.