Shopsmith Forums

keakap wrote:Sorry, I wasn't clear. The bench tube clamps as I called 'em are listed as "tube lock bar", and are used to clamp the bench tubes to the headrest.
The contact surface is small, and the contact surfaces of the bench tube to the headrest are also quite small.
Looks strong enough, but the fact is still that the spt tubes are not perpendicular to the bench tubes. I can't figure out how anything would align properly in this circumstance.

Before I tightened the 'tube lock bar bolts' (say that three times fast) the whole Mark V would do a hula with me grabbing the carriage and shaking it, btw.

Another btw: even with the caster assemblies tightened while the assy. at its highest possible position (not a hole lotta playway) there's still some caster drag at fully retracted position (so the M5 is not completely supported by legs only). I don't recall if this is the normal position. I mean when you're not having problems little stuff like that falls under the "So what?" category.
Come to think of it, other than a minor annoyance of having the machine slide unexpectedly on its barely engaged casters, so what?

dusty wrote:Do the Headrest and Base not have cast locators (pressure points) that position the tubes while the lock bars just force the tubes into proper position and lock them there? If the "pressure points" do not relate to one another properly, you will have to compensate for that as you assemble the base unit.

To achieve the precise relationships that I believe you are talking about, your Mark V must be assembled that way - checking for perpendicular, horizontal, and parallelism as you go. To achieve this without pulling my hair out, I do assemblies on a bench top that I believe to be reasonably flat and stable.

You mention the carriage in your post. If the carriage is already in place, meaning you have also installed the way tubes, realignment is going to be difficult. There are just too many opposing forces to deal with. To get precision relationships at the end, you have to creep up on it (beginning with just the bench tubes, headrest and base. If you get there any other way, you are just plain lucky.

Do the Headrest and Base not have cast locators (pressure points) that position the tubes while the lock bars just force the tubes into proper position and lock them there? If the "pressure points" do not relate to one another properly, you will have to compensate for that as you assemble the base unit.

Okay. A closer look and a re-read brings more light (to that otherwise barren darkland between my ears).
The cast locators/ pressure points are, it turns out, what I was calling casting ridges. Present in both the parallel and perpendicular planes related to the bench tubes, they, and one spot on the main casting body, support the bench tubes (force and lock). It will be possible to shim these if necessary.
I was fascinated to see that on the Base end (right) there is also a 'point' (one each) that stops the tube- that is, "bottoms" it in the casting as it is installed. Well, actually what fascinated me was that there is no such 'stop' in the other (headrest/ left) end. One presumes feng shuei is invoked.

To achieve the precise relationships that I believe you are talking about, your Mark V must be assembled that way - checking for perpendicular, horizontal, and parallelism as you go. To achieve this without pulling my hair out, I do assemblies on a bench top that I believe to be reasonably flat and stable.

I flipped the gutted sucker over on a couply stout cardboard cartons so I could get a better look. Now I'll move it onto a flat surface for surgery. I have a solid wood core external door here for just such porpoises. Or, as I study the particulars, I may have to bring down one of my collector's items from the shelf- a 3/4 x 16" x 8' board. (Remember those? In our first apartment was a "shelf" on concrete blocks. Remember those?). I envision drilling four (2 & 2) 1" holes in appropriate locations to access, from underneath, the four bolts that secure the bench tube lock bars, as the whole assy. sits on the board upright and "registered" on the board in one plane. I think I need to have the base of the Headrest casting and the base of the Base casting solidly on that one common flat surface. There's so much slop!

You mention the carriage in your post. If the carriage is already in place, meaning you have also installed the way tubes, realignment is going to be difficult. There are just too many opposing forces to deal with. To get precision relationships at the end, you have to creep up on it (beginning with just the bench tubes, headrest and base. If you get there any other way, you are just plain lucky.

dusty wrote:The following show what can be done to establish the proper orientation between Bench Tubes and SPT Tubes (here I have used an Extension Table).

I believe that this relationship must exist (by luck or otherwise) in order to obtain optimum alignment later.

dusty wrote:...
I now realize, however, that my Base and my Headrest are not cast the same. I can insert the Bench Tubes much farther onto the Base than I can into the Headrest.
...

JPG40504 wrote:JMHO................

https://forum.shopsmith.com/viewtopic.php?p=41342#post41342

keakap wrote:I agree that the spt and the bench tubes must be perpendicular, as shown. This was Far from the case with mine when I started. I think we're on to something.

Query, or observation: are you using the carriage to eliminate any possible false readings from bench tube sag? Just curious. What is really important now is that the Base and Headrest be in line, who cares what goes on in between, imho.

Nice pics. .