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Alignment puzzle
Posted: Fri Feb 04, 2011 10:22 pm
by denver
Hello,
I'm having a little trouble getting the main and extension tables aligned. It's fine with the main table moved all the way to the right, up to the extension table. In that position they're flat with respect to each other. But if I slide the main table all the way to the left, the two surfaces no longer line up. It's as if the main table is tilted to the right (clockwise) a bit. When I lay a straightedge across the two, there's a gap of about 1/8" at the right hand edge of the main table. More in the back than the front. The main table is square to the headstock spindle. The machine is about 40 years old. It's been upgraded, first to a 510, then to a 520.
Any helpful ideas or suggestions would be appreciated.
Regards,
Denver
Posted: Fri Feb 04, 2011 11:26 pm
by SDSSmith
denver wrote:Hello,
I'm having a little trouble getting the main and extension tables aligned. It's fine with the main table moved all the way to the right, up to the extension table. In that position they're flat with respect to each other. But if I slide the main table all the way to the left, the two surfaces no longer line up. It's as if the main table is tilted to the right (clockwise) a bit. When I lay a straightedge across the two, there's a gap of about 1/8" at the right hand edge of the main table. More in the back than the front. The main table is square to the headstock spindle. The machine is about 40 years old. It's been upgraded, first to a 510, then to a 520.
Any helpful ideas or suggestions would be appreciated.
Regards,
Denver
Many Mark V's have a screw located in the headrest under the tiebar (on the back side). This can be use to "twist" the way tubes and affect alignment of the machine.
Alignment Puzzle (Extension Tables)
Posted: Sat Feb 05, 2011 7:03 am
by dusty
denver wrote:Hello,
I'm having a little trouble getting the main and extension tables aligned. It's fine with the main table moved all the way to the right, up to the extension table. In that position they're flat with respect to each other. But if I slide the main table all the way to the left, the two surfaces no longer line up. It's as if the main table is tilted to the right (clockwise) a bit. When I lay a straightedge across the two, there's a gap of about 1/8" at the right hand edge of the main table. More in the back than the front. The main table is square to the headstock spindle. The machine is about 40 years old. It's been upgraded, first to a 510, then to a 520.
Any helpful ideas or suggestions would be appreciated.
Regards,
Denver
I'm reading between the lines, sorta. I conclude that you have two extension tables. If so, I recommend that you identify one as right extension and the other as left extension and then use them that way whenever table top alignment is important to you.
It has been said that they can be aligned so as to be interchangeable and I agree. They can be but in the real world they don't stay that way. If you move your Mark V around and if your shop floor is not perfectly flat, this alignment will be effected.
The Mark V is not a solid mass. It is very flexible as a direct result how the tubes are connected to their respective support members. The headrest mates with the tie bar and the locking mechanism is nothing more than a friction catch. No great stability there. At the other end, the base mates with the base arm and are held together by a hinge configuration. There is some movement there. All of this is held together with setscrews.
Couple all of that with the ability to go vertical for drill press operations and then back horizontal for the other functions - it is not hard to see why maintaining precise alignment can be a challenge. BUT - it can be done.
I hardly ever move my Mark V. My garage floor is, by design, not flat. It slopes toward the door so as to not collect water in puddles on the floor. If I lived in snow country and I parked the car in the garage this might be a neat feature. But I don't, therefore it is a nuisance that I must live with. Oh yes, in addition to being a nuisance, it is also 'building code'. I block one end of my Mark V to compensate for the slope.
Put a level on the tubes (lengthwise) and across the tubes at various locations and you will see the results of what I am saying. If yours is level in all directions at all locations, you are fortunate and precise alignment should not be a problem. Otherwise, if this precision is necessary, you will have to tweak now and then.
Posted: Sat Feb 05, 2011 11:40 am
by denver
Thanks for the replies.
Rob, I didn't think of that screw until late last night. It should take care of the front to back difference. I'm still puzzled about the side to side difference though.
Dusty, I just have one extension table, installed on the right, as usual. I can adjust it flat with respect to the main table when the main table is all the way to the right, as per the instructions. If I check again after sliding the main table to the left (making no other changes), it's no longer flat. If I then slide it back to the right, it is. As I move the main table farther from the extension table, the worse the alignment is. When I say flat, I mean that a straightedge laid across both tables shows no gaps between the straightedge and either table surface.
I agree that things are a little bit flexible, but all I'm doing is sliding the main table back and forth, so I wouldn't expect as much difference as I'm seeing. One possibility that I thought of is that the main table isn't quite parallel to the way tubes when it's perpendicular to the saw blade. That would cause a gap to appear between the straightedge and one table or the other, increasing as the distance between them increases. Has anyone encountered this kind of situation before?
Regards,
Denver
Posted: Sat Feb 05, 2011 12:24 pm
by dusty
denver wrote:Thanks for the replies.
.....
Dusty, I just have one extension table, installed on the right, as usual. I can adjust it flat with respect to the main table when the main table is all the way to the right, as per the instructions. If I check again after sliding the main table to the left (making no other changes), it's no longer flat. If I then slide it back to the right, it is. As I move the main table farther from the extension table, the worse the alignment is. When I say flat, I mean that a straightedge laid across both tables shows no gaps between the straightedge and either table surface.
.....
Denver
I think this means that you have "a twist" in the tubes. Said another way, the Way Tubes are not in parallel planes with the bench tubes. If sitting on a perfectly flat floor, I would expect that you to have some diagonal rocking.
This could be caused by the tubes having been inserted into their respective sockets and the set screws tightened without the tubes being properly oriented OR by one leg sitting higher (or lower) than the others when the set screws were tightened.
Posted: Sat Feb 05, 2011 1:02 pm
by denver
Thanks Dusty. That's what Rob suggested also. I'll check that. I'm trying to visualize the effect that would have. It seems to me that if there was a twist, I would see a difference in the gap front to back. In an extreme case, one table would appear to be too high in the front and too low in the back. I do see a slight difference in the gap, front to back, so there is indeed a bit of a twist. But what I also see is a gap left to right, that's consistent (mostly) front to back. I've attached an exaggerated drawing to help illustrate. Would a twist have this effect?
Thanks,
Denver
Posted: Sat Feb 05, 2011 2:11 pm
by wa2crk
Denver;
Good to have you aboard!! A question that I have is "are the way tubes straight? The set screw in the frame will correct any front to rear twist in case the table slopes down to the front when sliding the main table from right to left. With the table sloping down from left to right indicates to me that the table tubes are not remaining vertical when the main table is moved to the left end of the machine. Check the tubes for straightness and while you are at it there is one other check that can be made. This may not cure your problem completely but accordiing to some experts the welded seams in the way tubes should be oriented the same. If you look into the tubes you will see the welds and they should be oriented the same so that both are down. This helps a lot with the lift assist. If you have a digital anglr such as a Wixey you can check the table legs for vertical at the right end and again at the left end. I have a hunch that they will be different.
At any rate keep us posted.
Bill V
Posted: Sat Feb 05, 2011 3:35 pm
by billmayo
[quote="wa2crk"]Denver]
The use of the Wixey digital angle gauge has save me many many hours of setup and alignment time in the past 5 years. This is one of the best tools I have purchased and recommend all Shopsmith owners have one. I use it often and am still finding new usages for the Wixey. It provides a real quick way to check previous alignments.
Posted: Sat Feb 05, 2011 3:52 pm
by dusty
denver wrote:Thanks Dusty. That's what Rob suggested also. I'll check that. I'm trying to visualize the effect that would have. It seems to me that if there was a twist, I would see a difference in the gap front to back. In an extreme case, one table would appear to be too high in the front and too low in the back. I do see a slight difference in the gap, front to back, so there is indeed a bit of a twist. But what I also see is a gap left to right, that's consistent (mostly) front to back. I've attached an exaggerated drawing to help illustrate. Would a twist have this effect?
Thanks,
Denver
NO, Denver. If I am reading your sketches correctly, it appears that the main table is not square to a plum line dropped off of either the front (infeed) or rear (outfeed) edge of the table. Followed by an extension table whose top surface has be adjusted to be in the same plane as the main table.
Is the blade square to the main table top?
STOP! I am guilty of making far too many assumptions here. What tools are you using to do your Main and Extension Table alignments.
These can be done with a glass of water and a weighted string and a ruler OR with a bubble level and a square OR with a Wixey like Bill has suggested. One is more time consuming than the other but reasonable accuracy is achievable with any of the three. Check with the architects and builders of the pyramids if you are in doubt.
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All tables are in the same plane as indicated by a 5' level.
With a Wixey, you would like to be able to move it to all locations on the Bench and Way Tubes and get this same relative reading.
[ATTACH]11802[/ATTACH]
Wixey Zeroed Here and then moved along all the tubes checking for relative position. If the same reading was achieved everywhere the tubes would be perfect. I hope for everything to remain within +- .3 degrees.
Posted: Sat Feb 05, 2011 4:42 pm
by dusty
More of thew same:
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[ATTACH]11807[/ATTACH]
[ATTACH]11808[/ATTACH]