Longer tubes

[edma194]

Plain cement or plaster might come apart from vibration but fiber reinforced concrete should work well. It shouldn't trap moisture if the tube is filled and the mix has the proper amount of water in it. As long as the mix is rammed into the tubes it will react with all the water and keep the tube sealed. I would worry a little bit about the tubes warping as the mix sets. That shouldn't be a problem with the bench tubes, and still seems unlikely to affect the way tubes if you give the mix plenty of time to set while held down on a flat surface.

My calculations may be way off here, but it looks like filling 54 inches of tube with concrete will add about 2.75 lbs. per tube. Perhaps not worthwhile for adding 11 lbs. total weight. But it would help stiffen the tubes.

[chapmanruss]

Dusty said

In all the years I have been on this forum I have not heard of a serious problem with "bent" tubes.

I know of only one case of bent OEM Way Tubes on a Mark V. I met the owner of a wood shop near me who uses a Mark V in his production of custom pieces. He had replaced the Mark V Way Tubes with the Model 10ER thicker Way Tubes because his had bent. He did not go into what happened to bend them. Pretty sure it wasn't under normal use.

[edma194]

Noticeably bent or crushed would be unusual but owners have had to rotate their way tubes to keep them close enough to parallel for the headstock to slide easily. I think a lot of tubes aren't quite straight as a result of headstock weight in the middle.

The most recent tubes from Shopsmith are made of stainless steel. Plenty of tensile strength but they have a thinner wall and come with the ends plugged to prevent crushing. I don't think crushing should be a problem for way tubes but the bench tube clamps could be over-tightened.

[chapmanruss]

I was just out in the shop and measured a set of Way and Bench Tubes from a 1957 Mark 5 that is disassembled. The wall thickness measures at about 0.125 so nearly the same as the one in the chart JPG recommended. My measuring could be off slightly.

[Dmd003]

Did some googling... Apparently concrete filled steel tubes are a common thing in construction. I ordered the tubes today, 57 and 57.75, so I'll get an extra 5 inches or so. Going to spray the insides with rust stop, or maybe just wd40, then fill with cement.

[Dmd003]

So, ordered from metalsdepot... And they don't fit. They definitely have a greater outer diameter than the shopsmith original tubes. It's close, and it goes through the headstock opening, but is too thick for the end support openings. I ground the ends a bit, but still couldn't jam it in. Ended up putting it back together with the original tunes, and somehow lost one of the set screws that holds the end cap into the waytubes. If anyone knows what size those are, I'll need to hunt one down. I'm going to see if i can grind more off the diameter at the ends, maybe using the belt sander.

[chapmanruss]

Thanks for the update. Odd that the Headstock would slide on but that the new tubes would not go into the bench ends.

[Dmd003]

Yeah, I used my grinder to take a little diameter off the ends, and was able to use a rubber mallet to get one end on the waytubes (the unfixed end), but not nearly enough for the other 6 ends to fit.

[jsburger]

Just curious. What is the OD of the SS tubes and what is the OD of the tubes you ordered from Metals Depot (measured by you)? Do the Metals Depot tubes meet the spec on their web site?

[Dmd003]

Not sure... I don't have anything accurate enough to measure that. And when you order a specific length from them, I don't think they accept returns.