Shopsmith Forums

First thread I've started, please bear with me.

I have a Mark V 500 and an extra headstock both with single bearing quills. I am wondering if I can press the bearing off the quill from the extra headstock and install it on the one that I use all the time to create a two bearing quill. Technically I know this can be done, but I guess my question is:

What measurement should the second bearing be away from the other? Does it matter? Has distance between to bearings been tinkered with to see what the best side runout can be achieved?

After answering those questions, does anyone have a "best way" to do this?

You can, but you would need to spin down the diameter of the spindle on a lathe. This is the area behind the existing bearing which currently forms a shoulder for the current bearing.
I did this approach instead:
http://www.shopsmith.net/forums/showthr ... t=upgrades

holsgo,

I have read your upgrades thread with interest. I too have a single bearing quill and the bearing will need to be replaced soon.

You mentioned the size of bearings you purchased and then said you made a shim to go between the new bearings and quill. How did you make the shim? What material did you use etc. And then of course you mentioned hand machining the quill housing so the bearings would fit there as well. I'd like to more specifics on that as well.

Thanks

terrydowning wrote:holsgo,

I have read your upgrades thread with interest. I too have a single bearing quill and the bearing will need to be replaced soon.

You mentioned the size of bearings you purchased and then said you made a shim to go between the new bearings and quill. How did you make the shim? What material did you use etc. And then of course you mentioned hand machining the quill housing so the bearings would fit there as well. I'd like to more specifics on that as well.

Thanks

You need a very accurate machine shop to do any machining on the quill housing and shaft for the second bearing. There are several opinions about where this second bearing should be located. After several years of testing, I believe adding the second bearing behind the front bearing is the best overall location.

I have available the modified quills plus my opinions for location and machining specs for adding the second bearing on the Gilmer and Poly-V single bearing quills.

I was inspired by Bill however I took a laymans approach since I didn't have access or money to machine down the shaft to accept a 5/8 bearing. I accepted that I could only get as close to the shaft behind the current single bearing with a 22x32x7. This meant that if I could get a good fit onto the shaft then the only machining would be inside the quill itself to accept the bearings.
The sleeve I made was out of aluminium flashing. This was the pefect thickness that, when epoxied round the shaft took up the slack. The flashing was carefully cut to round the shaft and not overlap. Then using bar stock I formed the sleeve by rolling the bar over the sleeve to create a curling effect. Similiar like when to roll paper. It may work best to do this prior to cutting it to size. It was my first crack at it. Then, I put this sleeve round the shaft covered in Polyurethane glue (as it foams it takes up space). Then I used the bearings themselves to hold the sleeve while the glue cured. I later removed the bearings and cleaned up the sleeve with a file. Be sure to not allow the sleeve to rub the back of the single bearing.
Next was machining the quill. This was done using a series of sanding drums with coarse grit in a drill. These days I would do it differently using my now working shopsmith and a grinder (but that's impossible if you are dismanling your shopsmith.) I used my calipers to get the measurement of the quill wall, determined the depth inside the quill it would take to fit the 3 bearings and began removing metal with the drum sander. I constantly checked the wall thickness to be consistant all the way around. It took a while but I would grind, check, fit for a tight fit. After some time I managed to get it perfect. I think.
Now that I'm done with a working shopsmith with my cross slide I could simply mount another quill in my chuck and using my steady rest and cross slide hold a dremel with a grinding wheel to more accurately do this task.

allmond2002 wrote:First thread I've started, please bear with me.

I have a Mark V 500 and an extra headstock both with single bearing quills. I am wondering if I can press the bearing off the quill from the extra headstock and install it on the one that I use all the time to create a two bearing quill. Technically I know this can be done,

a "best way" to do this?

As cheap as replacement bearings are, I wouldn't even consider going thru the effort to pull a good bearing off a good quill to experiment with an "improvement" that has been debated here as to whether or not it is truly beneficial. But that's just my opinion.

I didn't know if this was a debate of whether it's beneficial. It was a question of whether it can and how to be done. There is no doubt that the upgrade is beneficial if you are considering runout and the ability to sustain side thrust an issue. I am seeing .001 of runout since the upgrade compared to +.005 and that's right at the spindle end. I am, however, looking for more tight tolerances than most.

holsgo wrote:I didn't know if this was a debate of whether it's beneficial. It was a question of whether it can and how to be done. There is no doubt that the upgrade is beneficial if you are considering runout and the ability to sustain side thrust an issue. I am seeing .001 of runout since the upgrade compared to +.005 and that's right at the spindle end. I am, however, looking for more tight tolerances than most.

In my opinion, if you have managed to get your measured runout down to .001 you have achieved your objective to the finest degree that you are going to be able to maintain on the Mark V.

I'm curious. Why do you 'need' that tight tolerance? I do not mean to challenge, I am just curious what sort of wood work you typically do that demands that degree of precision. I am guessing that it is your metal work and not your wood work.

Dusty, you are correct. Any metal puts additional side thrust. However, routing wood itself has side thrust. Either way, I didn't like the fact the spindle, when mounted in the quill and before it was slid into the headstock, could be deflected by hand. Didn't give me much confidence.

holsgo wrote:Dusty, you are correct. Any metal puts additional side thrust. However, routing wood itself has side thrust. Either way, I didn't like the fact the spindle, when mounted in the quill and before it was slid into the headstock, could be deflected by hand. Didn't give me much confidence.

BUT... Did you try installing a new single bearing and check it like that. My challenge to the whole process in the case of 95% of users here has always been that slop of a new 2 bearing quill has constantly been compared to a worn single bearing instead of a new single bearing. I contend that doing it like that is bad science.
I understand your application and if I were doing light metal work I too would probably use a 2 bearing quill pretty much automatically. The thing that bothers me is not comparing new bearings to new bearing or old bearings to old bearing...
We have discussed these 2 bearing quills so much that we have convinced a lot of people that the original single bearing quill is junk and needs to be gotten out of there as quickly as possible and that they cannot possibly do good work with one.
You (and others) keep talking about side thrust with a router bit. The side thrust from a router bit is nothing compared to the side thrust of a 10 saw blade cutting through a piece of hard 2" oak. That blade has a huge amount of leverage on that arbor. Or how about a big out of balance hunk of tree crotch attached to a faceplate in lathe mode.
I have no problem with 2 bearing quills and have a couple. I just have a problem with giving credit to a second bearing in going from +.005 run-out to .001 run-out when a new single bearing could have easily given the same amount of improvement.
We have done pretty much the same thing with tables. We have spent so much time talking about tables (don't misunderstand, I like all of the discussions) that we have convinced an awful lot of new or potential users that the original 500 tables are a piece of crap and virtually unusable... We really know better than that.
As I said I love the discussions but we at least owe folks "good science" rather than the approach that if 1 is good 2 has to be better or that 37 bearings would be really great...
All I am asking for is that we quit comparing 2 new bearings to 1 tired worn bearing and saying that such a comparison validates a second bearing for most users.