[Shaper] Little problem with shaper table

[Tom Griffin]

Ron,

The upper nut pinned to the outer screw looks original. That would serve the same purpose as the inner threads on nut in the drawing I provided and would force the inner screw to do the initial lifting of the table. The lower pin hole in the outer screw could have been attached to a flanged collar, now long gone since it probably fell out the bottom when the pin broke, to restrict its upper travel. Everything makes sense except for the lack of a collar on the bottom of the inner screw. Without one, the inner screw would never turn the outer screw when it reached its upper limit and cause the whole assembly to telescope. Can you see the lower end of the inner screw?

Tom

 

[peacock]

Scrapmetal: The nut is not solid in the table is it ? Have I missed something here? I think the inner shaft turns till it runs out of threads at the top then it turns the nut that in trun turns the outer screw by means of the set screw locking them together. At the bottom some device keeps the nut from screwing off the end of the inner screw and the process is reversed. If this is what everyone is already said please excuse my lack of understanding.

 

[ScrapMetal]

Assuming that both are left hand, same pitch, I have a vague idea that one turns (the easier one, the smaller one) until it runs out of travel, and somehow locks up and starts to turn the larger one to increase the ultimate overall length. On the smaller screw, do the threads run off the end, or does it (or perhaps did it) shoulder out? Or perhaps the dog point is timed to lock in at a certain length? It's hard to say for sure that you even have all the pieces for sure at this point.

I'm pretty sure some things are missing. Both threads are left hand and look roughly to be the same pitch. The threads do run off the end of the smaller screw. As for which one moves first, I have a theory. Maybe not a good one but a theory anyway. To start, let me refer you back to these pics of the "fitting" that the smaller screw comes out of.





The "fitting" is a loose friction fit inside the top of the outer sleeve. I'm thinking that at it's lowest position, the fitting will be entirely inside the sleeve and snugged up to that upper flange. The friction would cause the outer sleeve to turn with the fitting/flange. When the travel of the sleeve is halted (some kind of plug/stop pinned to the bottom where the broken section is) continuing to turn the inner screw/flange will over come the friction and the inner screw would then continue to raise the table. In order for that theory to work it would need a smooth sleeve, threaded on the inside for the screw to engage, that fits inside of the outer sleeve.

Here's what I'm thinking:


The "inner" sleeve would be pinned to the outer sleeve down below where the chunk is missing. It would flare out on the bottom in order to engage the bottom skirt of the nut and "stop".

Thats exactly the way my great big no name drill press table works. Thinking hydraulics wouldnt be a
bad idea either always a way out.

That would certainly work. Perfect "plan B" if it becomes too expensive or impractical to fix it. Hadn't occurred to me. Thanks!

Ron,

The upper nut pinned to the outer screw looks original. That would serve the same purpose as the inner threads on nut in the drawing I provided and would force the inner screw to do the initial lifting of the table. The lower pin hole in the outer screw could have been attached to a flanged collar, now long gone since it probably fell out the bottom when the pin broke, to restrict its upper travel. Everything makes sense except for the lack of a collar on the bottom of the inner screw. Without one, the inner screw would never turn the outer screw when it reached its upper limit and cause the whole assembly to telescope. Can you see the lower end of the inner screw?

I just can't believe that the two screws were supposed to be pinned together. That would limit the table travel to maybe six inches total. The inner screw is threaded all the way off the end and the end is rounded like you would do if it's meant to engage/re-engage in a shaft. I do believe there was a pinned lower collar though. I am also thinking, as I showed in the pic above, that the lower "collar" was attached to another shaft that went inside the big outer sleeve.

Tom

Scrapmetal: The nut is not solid in the table is it ? Have I missed something here? I think the inner shaft turns till it runs out of threads at the top then it turns the nut that in trun turns the outer screw by means of the set screw locking them together. At the bottom some device keeps the nut from screwing off the end of the inner screw and the process is reversed. If this is what everyone is already said please excuse my lack of understanding.

No, the nut isn't solid in the table. I tried to get the set screw backed out that is holding it in earlier today. Spent about a half hour with a four pound mallet and an impact driver to no avail. Put some Kroil on it and will try again tomorrow.

 

[ScrapMetal]

After another hour or so trying to back out the set screw holding the nut on and I've given up. Time to get serious. I drilled through the set screw but not knowing if it's fine or coarse threads I stopped short in diameter so I don't bugger up the threads. As solid as it is in there I think that an "easy-out" would only gouge some metal out. I'm planning to pick up a can of "freeze spray" or something of the kind and try to shrink the remains of the set screw before trying to back it out.

-Ron

 

[kdupuis]

A little heat can be your friend.

 

[ScrapMetal]

A little heat can be your friend.

I considered that. Couple of problems though. First is that the set screw is an a fairly large hunk of cast iron firmly snuggled in an even larger pile of cast iron. A lot of heat would have to be applied to have any kind of effect. Then there is the fact that it is covered in old flaking paint (without a doubt toxic), Kroil (also don't want to smoke it), as well as other misc. unknown oils and greases. Lots of it too. Applying a torch to it would generate quite the toxic cloud and could conceivably even spread fire to other areas of the shaper.

Earlier today when I was drilling out the set screw I got a wiff from a little bit of smoke coming off the hot drill bit/screw/chemical combination. Almost instantly it felt like I had a severe sore throat. I stopped drilling and stepped away from the work for a bit, got some fresh air, let the air clear and the feeling slowly subsided. I was careful not to inhale near the work while finishing drilling but I still have a bit of a "tickle" in my throat some eight hours later.

Never had that happen before and don't intend to let it happen again. For now, I'm going to give the "freeze" thing a try even though I know the application of both would theoretically give the best results.

Thanks for the suggestion though,

-Ron

 

[ScrapMetal]

I was able to remove the "nut" today with a combination of a very large "EZ-out" and a combination "freeze"-penetrant. All is good! I need to modify my theory though and it needs to lean back to what Tony proposed. Once I got a better look at the tip of the screw I found that it wasn't threaded all the way off the end.



There is a "pin" sticking out of it so it must be intended to stop on or catch something.

Another little "feature" on the other end of the screw, that I failed to mention, makes me wonder if it isn't set up to "drive" something as well.


Possible that the "notch" in the drive collar was supposed to mate up with something?

While I'm at it here are a couple shots after removal of the "nut". This one is where the nut sat with one of the set screw holding it in. Fortunately I only need to remove one to pull the nut.


The "nut" itself. Pretty straight forward. No notches, no machined surfaces to act as a bushing or run a bearing against, etc.


Now I'm going to go back over the drawings and suggestions that were offered up and see if I can put together a better hypothesis given the new information.

While I'm at it though, I'm looking for suggestions as to how to go about fixing or replacing that threaded sleeve. If I'm to make a new one what would be the best material to use. Currently I believe it's cut from cast but is there something a little more "available" that would wear/function as well or better?

Thanks guys,

-Ron

 

[peacock]

OK this is what I thought you would find. In my previous post when I said nut I was talking about the one at the top where the outer sleeve and "nut" were set screwed together. not the nut on the bottom. I think the pin on the inner screw cacthes on that notch on the top nut and turns it which, as I said before turns the outer slevve in the bottom nut

 

[Tom Griffin]

Ron,

I'm not surprised to see a shoulder and pin on the lower end of the inner shaft. There was likely a collar on there at one time that was at some point ripped off. That means the piece on the upper end of the same shaft is actually a nut. I suspect that nut was pinned to the outer shaft and was also ripped off by whatever catastrophic event got the lower collar.

Tom

 

[peacock]

I think the fix is really simple. Drill and tap a new hole 180 from the damage hole top and bottom put it back together.