Bandsaw - How Much Wobble is OK

[dusty]

I must not understand the problem. Is the wobble with the legs (eccentrics) when they are seated in either the headrest or the base arm assemblies OR is it when they are inserted into the bandsaw castings.

I can not eliminate the movement completely with either of my bandsaws in any of the six locations where they could be mounted but the "wobble" is minimal. I am saying this after using both the original eccentrics and straight tubes.

It might be significant to note that I have the longer eccentric legs inserted into the bandsaw.

When I remove sleeve and insert assembly I find that the two studs are not screwed in the same amount. If they are "balanced" (screwed in equally), I do get a bit more "wobble". I assume that this is due to the eccentrics not being secured equally.

[algale]

Ed, regarding your question, since I too am also experiencing this issue, I will try to take a look and answer your question about whether the bolts are free to move into the bores this weekend. A warranty claim is an intriguing idea. On the other hand, that would preclude me from going for the double-tilt upgrade (which I have been trying to convince myself that I need ).

JPG, I will similarly try to answer your question about the opposite end casting. I rarely mount things there other than the auxiliary table but I know there is some degree of wobble in it because when using the aux table in conjunction with the main table, I have to take that wobble into account while clamping or the table will not be level with the main table. But I will try to get some objective measurements this weekend to measure the amount of wobble. I will first try my band saw. My plan is place a wixey on the band saw table aligned along the long axis of the Shopsmith and see how many degrees of wobble I get from vertical in both directions (toward/away from headstock) both pre claming and with clamping. Then I'll move the band saw to the other end and repeat those measurements. Then I'll switch to my aux table and repeat the measurements. I expect I'll get less wobble from the aux table because of its longer tubes and because the connection between the tubes and table is rock-solid (unlike the band saw where what is going on inside the band saw case with the the tubes might contribute to wobble).

Dusty, when you say the "longer" tubes are in use on your band saw, I'm not sure what you mean. I thought there was only one length eccentric for the band saw. But other things being equal, longer tubes will reduce wobble.

[dusty]

Ed, regarding your question, since I too am also experiencing this issue, I will try to take a look and answer your question about whether the bolts are free to move into the bores this weekend. A warranty claim is an intriguing idea. On the other hand, that would preclude me from going for the double-tilt upgrade (which I have been trying to convince myself that I need ).

JPG, I will similarly try to answer your question about the opposite end casting. I rarely mount things there other than the auxiliary table but I know there is some degree of wobble in it because when using the aux table in conjunction with the main table, I have to take that wobble into account while clamping or the table will not be level with the main table. But I will try to get some objective measurements this weekend to measure the amount of wobble. I will first try my band saw. My plan is place a wixey on the band saw table aligned along the long axis of the Shopsmith and see how many degrees of wobble I get from vertical in both directions (toward/away from headstock) both pre claming and with clamping. Then I'll move the band saw to the other end and repeat those measurements. Then I'll switch to my aux table and repeat the measurements. I expect I'll get less wobble from the aux table because of its longer tubes and because the connection between the tubes and table is rock-solid (unlike the band saw where what is going on inside the band saw case with the the tubes might contribute to wobble).

Dusty, when you say the "longer" tubes are in use on your band saw, I'm not sure what you mean. I thought there was only one length eccentric for the band saw. But other things being equal, longer tubes will reduce wobble.

The legs on my eccentrics measure about 4" on one and only 2" on the other.

Bandsaw Eccentric.png (29.37 KiB) Viewed 12878 times

[DLB]

Some updates, answers, and clarifications are in order. Also, I'm suddenly concerned whether I'm following front/back and left/right convention and can't recall where I've read it. Left - I think there is no debate, it's the end with the headrest casting. When I've been saying front, I'm referring to the face of the machine that has a power switch and speed control, and I know there is some disagreement. Please let me know if I'm not following the convention.

I do not detect any interference with the normal clamping motion of the SPT clamp. The insides of the square guide holes are painted so any interference should be readily apparent to eyeball/flashlight inspection, and mine were clean. I've over-extended the clamps and they move freely. Looking straight down on them you see something that is off, like they are not co-axial, but I think it is an optical illusion. At one point I was going to go back and take a harder look at that, but other findings caused me to rule it out. My plan was to find a piece of 3/8 square metal stock or make a piece of 3/8 square wood stock of the right length and see it it moved freely front to back engaged in both holes. Note that if there is a problem here it is still a headrest casting.

As we learn more about this, I see that much of my premise in the original post is true but irrelevant. The instability that I attributed to the eccentric mounts was overly simplistic and has more to do with this specific machine and possibly others that share its features. The dimensional features of the straight tube that make it inherently more stable than the eccentric on the SS end, specifically it is longer and larger in diameter, only serve to limit the amount of rocking in the left/right direction. The feature that makes the straight tube stable in this specific mounting hole is the stop collar. The two points of clamping that I'm getting only have to hold the tube down so the stop collar remains in contact with the headrest, to prevent rocking. If I clamp the straight tube in a slightly raised position, it also rocks in this mounting hole. I'm not endorsing the dimensions of the eccentrics, but my original suspicion that they seemed to be the source of the problem seems incorrect.

Everything about the base casting end of this machine looks and checks good. Visually, there is a tremendous contrast in the mounting hole condition compared to the headrest. I'll get pics and follow this up.

It would be enlightening to know how common, or uncommon, the differing clamp sockets in the headrest casting are. So far, we have mine and algale's. I looked at headrests on ebay last night and saw one that was definitely like ours, one that definitely was not, and a few where the photos provided were insufficient for that purpose. I can try polling this forum in a separate thread with more emphasis on what to look for. I'd ask manufacturing dates of machines with and without the feature if known. Anything else? Algale - age of your machine?

[dusty]

Some updates, answers, and clarifications are in order. Also, I'm suddenly concerned whether I'm following front/back and left/right convention and can't recall where I've read it. Left - I think there is no debate, it's the end with the headrest casting. When I've been saying front, I'm referring to the face of the machine that has a power switch and speed control, and I know there is some disagreement. Please let me know if I'm not following the convention.

I do not detect any interference with the normal clamping motion of the SPT clamp. The insides of the square guide holes are painted so any interference should be readily apparent to eyeball/flashlight inspection, and mine were clean. I've over-extended the clamps and they move freely. Looking straight down on them you see something that is off, like they are not co-axial, but I think it is an optical illusion. At one point I was going to go back and take a harder look at that, but other findings caused me to rule it out. My plan was to find a piece of 3/8 square metal stock or make a piece of 3/8 square wood stock of the right length and see it it moved freely front to back engaged in both holes. Note that if there is a problem here it is still a headrest casting.

As we learn more about this, I see that much of my premise in the original post is true but irrelevant. The instability that I attributed to the eccentric mounts was overly simplistic and has more to do with this specific machine and possibly others that share its features. The dimensional features of the straight tube that make it inherently more stable than the eccentric on the SS end, specifically it is longer and larger in diameter, only serve to limit the amount of rocking in the left/right direction. The feature that makes the straight tube stable in this specific mounting hole is the stop collar. The two points of clamping that I'm getting only have to hold the tube down so the stop collar remains in contact with the headrest, to prevent rocking. If I clamp the straight tube in a slightly raised position, it also rocks in this mounting hole. I'm not endorsing the dimensions of the eccentrics, but my original suspicion that they seemed to be the source of the problem seems incorrect.

Everything about the base casting end of this machine looks and checks good. Visually, there is a tremendous contrast in the mounting hole condition compared to the headrest. I'll get pics and follow this up.

It would be enlightening to know how common, or uncommon, the differing clamp sockets in the headrest casting are. So far, we have mine and algale's. I looked at headrests on ebay last night and saw one that was definitely like ours, one that definitely was not, and a few where the photos provided were insufficient for that purpose. I can try polling this forum in a separate thread with more emphasis on what to look for. I'd ask manufacturing dates of machines with and without the feature if known. Anything else? Algale - age of your machine?

I don't understand your reference to a "stop collar". Where in the band saw mounting scheme are you using a "stop collar"?

[DLB]

Shopsmith calls them Tube Collars in the Tailstock drawings, and they serve the same purpose on the bandsaw if you are using straight tube mounts. You adjust the height of the bandsaw to match the drive hub with the headstock, then lower the collar against the headrest and lock the collar to the tube with a setscrew to make a repeatable stop. Then the next time you mount the bandsaw you simply lower the tubes until the collars stop at the headrest.

[dusty]

The dawn breaketh. I understand now how Tube Collars (aka Stop Collar) enter into this discussion. They don't fit into my setup because I have eccentrics and never use stop collars with the bandsaw. Thank you for the education. I.m going to withdraw from this discussion because I have no experience with this setup using straight tubes. There is no way I could use them because I need the lateral alignment provided by the eccentrics.

I will make one departing statement however. The tubes, straight or otherwise must extend at least 4" into the bandsaw to gain stability there. I would also suggest that all set screws must be tight and the studs in the Sleeve and Insert Assembly must be making full contact with the tubes (straight or eccentric).

[DLB]

Here is the closeup of the inside the mounting tube that I referred to earlier. While this seems severe, it is relatively deep inside the hole. Too far down, I think, to have been caused by poor clamping of SPTs unless the original owner had older SPT mounts that extend farther down. Also doesn't look like you'd expect. Top of the damaged area is down ~1.7 inches from the top of the mounting hole.

Headrest Front Mounting Hole

IMG_7930 (2).JPG (194.52 KiB) Viewed 12809 times

[BuckeyeDennis]

From that photo, it looks to me as if the bottom of the hole is still rough casting, never touched by the boring tool. That could certainly explain some wobble. It may be that the rough casting was misaligned for machining, causing both the incomplete boring and the mismatched clamp-hole bosses that you reported in this thread.

If so, it may qualify for free replacement under Shopsmith’s lifetime manufacturing-defect warranty.

[dusty]

I'm sorry but I am still a doubter. I doubt that the condition of that bore is the cause of your wobble.

When the legs are locked the studs that secure them in the bores should be equally extended (into the bore). This caused equal locking pressure on the two legs. Have you checked that?

The images prove nothing. They serve only to guide the discussion. Note though that these bores are not pristine.

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