Shopsmith Forums

benmcn wrote:Well, I tried heating the quill, I tired the bearing puller on both sides all to no avail. Bearing puller is just working against itself. This needs to be pulled apart, problem is their is nothing to pull on. I do have an old single bearing quill, it just needs a new bearing.

Anyone have Skip at MKC Tools modify a single bearing quill to a double bearing quill?

Is a double bearing quill really that big of a deal? Seems like I read on the forum that the second bearing was added in an answer to the total shop marketing that they had two bearings making their machine better.

Although I have not done it I would have absolutely no qualms about having him modify a single bearing quill. His work is first rate. Check his web site. I think he has the modified ones in stock. I think all you would have to do is send yours to him and he will send you one already done.

Give him a call he does answer the phone. Ask him about your double bearing quill. I will bet he has the answer.

Strongly suggest you go to the well-known internet auction site and search for a 2 bearing quill by MKC tools.

Everything here, 2 day turn time, $95 + SH
http://mkctools.com/mark%20v%20parts.htm

Depends upon who you ask!

No question a double bearing quill is better. Question is when is that slight improvement needed? Also where does the second bearing go?

All a second bearing in the Mark V does is minimize the wobble effect of the splined shaft in the nylon coupling.

Two opposing design issues involved here.

The prime objective is to minimize output shaft runout(wobble).

Another important objective is to allow the shaft to extend and be driven by the drive sleeve. In a perfect(or $$$$) world the splined shaft will be perfectly straight, have no play in the splines/coupler junction and ditto for the coupler/drive sleeve junction. Oh also no play in the bearing(s).

Alas our world is neither perfect nor are we suffocating from all That $$.

If we be making a milling machine(gross side thrust) the added bearing(s) need to be near the output end of the shaft and any slop at the other end becomes less relevant. A large turning on a lathe is the same scenario.

However our bearings MUST have some clearance or friction becomes a problem. That is obvious from the little top hat in the single bearing Mark V/5 that centers the splined shaft in the quill body so as to make insertion of the far end of the shaft into the drive sleeve coupler easier.

So where to put the second bearing? Too far from the first bearing at the output end and shaft straightness becomes more critical. The further from the first bearing does indeed decrease runout.


It is a bunch of tradeoffs both from a goal standpoint and a manufacturability standpoint.

The fact that there have been design iterations illustrates it ain't easy/simple!

There is no BEST answer. Only better from different perspectives.

JPG wrote:Depends upon who you ask!

No question a double bearing quill is better. Question is when is that slight improvement needed? Also where does the second bearing go?

All a second bearing in the Mark V does is minimize the wobble effect of the splined shaft in the nylon coupling.

Two opposing design issues involved here.

The prime objective is to minimize output shaft runout(wobble).

Another important objective is to allow the shaft to extend and be driven by the drive sleeve. In a perfect(or $$$$) world the splined shaft will be perfectly straight, have no play in the splines/coupler junction and ditto for the coupler/drive sleeve junction. Oh also no play in the bearing(s).

Alas our world is neither perfect nor are we suffocating from all That $$.

If we be making a milling machine(gross side thrust) the added bearing(s) need to be near the output end of the shaft and any slop at the other end becomes less relevant. A large turning on a lathe is the same scenario.

However our bearings MUST have some clearance or friction becomes a problem. That is obvious from the little top hat in the single bearing Mark V/5 that centers the splined shaft in the quill body so as to make insertion of the far end of the shaft into the drive sleeve coupler easier.

So where to put the second bearing? Too far from the first bearing at the output end and shaft straightness becomes more critical. The further from the first bearing does indeed decrease runout.


It is a bunch of tradeoffs both from a goal standpoint and a manufacturability standpoint.

The fact that there have been design iterations illustrates it ain't easy/simple!

There is no BEST answer. Only better from different perspectives.

You are correct as usual. It is called a stack up in engineering terms. All the tolerances of all the components must add up to have the result you want on the output of the device. That does not necessarily mean that if you want a one thou run out tolerance on the output spindle that all the components of the spindle (bearings, bearing seats, concentricity, etc.) are all one thou tolerance. It depends on the + or - deviation allowed for the part. So the deviation allowance must be considered in the end item. Stack up.

As JPG says it is complicated but that is why we pay engineers the big bucks.

Perhaps it is time to call shopsmith? Yes it has to be put together but it could be destructively designed so removal is not going to happen.

The part #518208 spindle assembly is not an order-able part but that is really what you need. You could check with them maybe they make exceptions??

Ed

I contacted SS customer service. They were prompt in returning an answer to my email. They indicated that they did not offer the spindle assembly as a replacement part. They didn't respond to my question about the lack of a roll pin.

My conclusion: Shopsmith has at least three different double bearing spindle assemblies. If you have one with the roll pin consider your self fortunate, as you have a repairable spindle. If you have the spindle assembly with out the roll pin design you might be better off purchasing a new quill.

Thanks again to all the great forum members who took time helping me out with this.

Well time to order the new one and then get out the big hammer and do some destructive testing for us. I for one would like to see how they put this one together.

BTW do you know the time frame for this quill? I know they made some changes to the bearings for the new powerpro but perhaps there were other changes.....

If I ever take the quill out of one of my powerpro's I will take disassemble it to see what I have. Any one else with newer quills might want to keep this in mind as well since we get little good information from shopsmith on such changes.

Ed

The Headstock this assembly came from has a serial number of 120492. (manufactured in 1992). I bought this used from a popular internet auction and don't have any history on it.
If am able to get the spindle assemble apart via "destructive disassembly" I will post some pictures.

I have an older mark 5 and took apart the quill after I replaced it with a two bearing quill. the older quill has a roller bearing on the shaft about 3/4 inch long with a sleeve that fits over the bearing and slips inside the sleeve. Is this an older two bearing quill. the two bearing quill I purchased had two roller bearings as pictured here. I wasn't sure but it did not appear as if anyone mentioned this quill. Larry