Knowledge You Can Build On — Est. 1998
indexing problem
john Lucas
I was using my new Alisam indexing wheel yesterday and ran into a problem. The index pin which is a 1/4x20 screw with a knob sticks out too far to turn things larger than 8 1/2" in diameter. When you unscrew the pin it hits the wood. In this case my turning was right on the border of maximum size and I was able to complete the work. I really need to work on my spring idea for the index pin. It would be flatter and wouldn't require all the screwing in and out.
Re: indexing problem
John K Jordan
For now, use screw from back side? Use a bigger chuck or spindle extension?
JKJ
Re: indexing problem
Dave Delo
John,
You know much more about all this indexing stuff works than I do but after reading the post, I went and checked out my Alisam to see if I could duplicate. I have a heavy 3.75" from the Alisam to end of jaws. With that distance I don't see a problem getting the screw out even with the diameter piece you have. If your using a recess to hold the piece I could maybe see a problem depending on the position you put the upright pole.
My 3520B won't allow to put the screw in from behind because of the headstock. Maybe Robust would be different. Maybe just get a shorter length screw machined.
Re: indexing problem
Dave Paine
I went to the Alisam site to see what this looked like.
Is the vertical post 3/4in dia? Can this be replaced with e.g. 3/8in or 1/4in thick bar?
The problem with a sliding pin
Dick Coers
is the accuracy of the fit between the pin and bore. It takes nice machining to get a good sliding fit on both the pin and the stub section that fits into the index plate hole, or you get movement in the wood part.
Re: indexing problem
Dave Delo
Here's a side view that shows the upright post fairly close to the disk with a dummy bowl from the drying rack mounted in the chuck. If the bottom of the bowl extended out in the direction of where the knob is located, I could still get the screw all the way out with about 3/16" to spare. This piece has a tenon so if you were using a recess, I'd say 3/16" or 1/4" would be about the deepest I could go. There's still a little bit more the post could be moved towards the disk...but not much. I'd tend to think John's chuck isn't getting him out far enough to begin with.
Re: indexing problem
john Lucas
Well the problem is I'm turning a clock but it could be a platter. The chuck sits in a recess. When the index pin is screwed all the way out it touches the wood. I do like the idea of the chuck extender but it's a lot of money for something I wouldn't need very often.
Besides that just screwing and unscrewing the index pin is a real pain. Not bad when your doing 12 indexes but when your doing 24. And if you doing the basket weave illusions and doing something like 96 or 124 then it would get real old. That's why I want a spring loaded pin of some sort.
Re: indexing problem
john Lucas
I don't remember the thread size on this but it's probably close to 3/4 so if you wanted to use a 1/2" or 3/8" bar you would have to make a special adaptor.
Re: The problem with a sliding pin
john Lucas
I wouldn't think there would have to be any more tolerance than the pin already has. YOu need some tolerance no matter what method you use if you use a straight hole. Now the ideal hole would be tapered and the pin would be tapered. That way they would align exactly every time.
Re: indexing problem
Dave Paine
If you check the diameter of the thread and the tpi I can easily make an adapter.
May be 3/4in x 10 tpi unless the bar was turned down to e.g., 5/8ikn dia.
Re: indexing problem
john Lucas
Dave I have capabilities to make most anything. Appreciate the offer. I'm looking at 2 modifications. One is to extend the threads on the bottom and put a couple of thumb wheels so I can micro adjust the height and then lock it down. The second is to rig up a spring loaded pin of some sort, ideally one that can be moved to use other holes that are already drilled in the shaft. I might also add another rare earth magnet to the bottom. When I use the inner row of holes on the Alisam only one magnet sits solidly on my ways because of the distance between them. Adding one more magnet closer to the bar would eliminate that problem.
Re: Spring release pin *LINK*
Dave Paine
If you want a spring release pin, perhaps the style of sailing fitting pin will work.
Two tiny ball bearings to lock in place.
The style in the link you push or pull.
Another style has a button in the head to release the bearings which are a lot more expensive. Do a search for Ball-Lok Quick release pin.
Cannot add second link
http://www.westmarine.com/buy/west-marine--ball-lok-quick-release-pins--P002_065_009_003
If you extend the threads on the bar how will you adjust the height of the bar/hole without rotating the bar?
http://www.go2marine.com/product/22889F/sea-dog-stainless-release-pin-1-4-in-x-1-in.html
Re: The problem with a sliding pin
Dick Strauss
John,
You may consider adding a HDPE bushing around the sliding pin and drill a bigger hole for the bushing. Then the metal pin rides on the slick HDPE bushing surface, not metal to metal. With the HDPE bushing (or similar material) You can then make the pin fit more snugly without it binding. HDPE is pretty resistant to wear as well.
Re: The problem with a sliding pin
Dick Strauss
John,
Why not just shorten the bolt that locks the indexing wheel? It looks to be at least twice as long as it needs to be. Also, the closer the post is, the shorter the bolt can be, right?. You may even be able to index from the back side of the wheel once the bolt is shortened. All you really need is to go in a few threads since you aren't putting a lot of pressure on the indexing system. You can always thread more of the bolt if need be too.
For the sliding pin system, I would have a tapered pin and hole if possible. That way it will self align if the two parts are slightly out of alignment when the pin first touches the wheel.
Re: The problem with a sliding pin
john Lucas
I think I discussed the tapered pin idea either in this forum or another one. I will probably do that. It will have to be a very gradual taper because sometimes the router puts a fair amount of force on the wood so the pin needs to lock the turning very firmly. That's part of the reason I changed from the Ironfire index wheel to the Alisam.
Check out this thread and the spring loaded pin *LINK*
http://www.aawforum.org/vbforum/showthread.php?5834-Alisam-indexing-system&p=112369#post112369
There are standard alignment pins
Ken Vaughan
There is a system of steel alignment pins and matching reamers that have been around for years and years. Taper is 1/4 inch per foot and diameters range from tiny to herky.
Got a near full set second hand years ago.
No need to reinvent
