Making plans to build a concrete bowl lathe - opinions welcome.

[Tony Kahn]

Just out of curiosity how are you planning to orient them, if it is the way i am thinking (where the quarter is sitting will be oriented down 180 degrees from picture) you may have a problem with yourways not being even thickness making it hard for and hard on your locking block hitting it unevenly.

[Mark Norman]

Yer right Tony, regarding the orientation, but I dont see the thickness variation as being an issue as the locking block will be clamping at the same relative point along the ways.

[Tony Kahn]

My concern is that there wont be a flat to clamp, the bolt will actually flex the block, because of it not having flat and also you are losing contact area, the bottom of the ways are basically gonna be an inverted v causing only the outermost portion of clamp to make contact. but i guess if you are going to machine the clamp piece you can machine it to a conical shape to match the shape.

[Mark Norman]

Bingo Tony! Yer right on it. Besides the outer most part of the clamping block has the most surface area. And it would not be real hard to add a conical disc on top of the clamping block. The best part was the two 5-1/2' pieces of steel was....give me a guess... go ahead....
I'll wait...
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yep, doughnuts!, my favorite word...FREE!!

I priced 4" X 6" I beam structural steel and it was only $7 a foot, but thats still eighty bucks.

[Tony Kahn]

I know what you mean steel seems cheap when you first start pricing but it adds up quick, my little brother works in a shop that makes heavy equipment attachments. he makes alot of my tools for me, like this week he is making me a jamieson style hollowing rig (speaking of which i need to make another post) all totalled it is costing me 35 for steel and about 30 for CNC machine time.

[Mark Norman]

Thats prety cheap for the cnc time Tony, who did the programing?

I set the steel more or less in place, I need to fabricate a few more parts for it but I need to clean up the shop before I start making a bunch of sparks.

[Tony Kahn]

my little brother did the programming, and they charge $60 an hour but for the employees it is charged by the minute for run time rather than full hours, he did it after work and it is mostly to cover wear on the tooling. All he is doing is drilling a couple holes and then a couple rabbit's in the clamp block. These pieces are made out of AR500 so you can't just drill it on drill press.

[alex carey]

I love seeing the floor with tons of shavings on it.
Couple questions I probably missed.

Is that where the bed is going to be in the picture?
Is the bed going to be easily removable for larger turning?

[Mark Norman]

I love seeing the floor with tons of shavings on it.
Couple questions I probably missed.

Is that where the bed is going to be in the picture?
Is the bed going to be easily removable for larger turning?

The bed will be positioned at 12" below the center of the spindle to accomodate a tailstock from a 24 swing machine. It will have some adjustability built in for fine tuning it. Its about an inch and a half high in the pics.

It will be removable by taking out six 3/4" bolts, two through the headstock and four in the foot. Each beam weighs in at over 40 lbs so the bed when all done will be in the 110 pound range. I'll weigh it when its all welded up. Not a big deal to remove it with the use of my overhead trolly hoist though.

[Gary Conklin]

Mark

Why not just lower the ways and fab a tailstock from concrete? seems like that would be a no brainer for you?

[Mark Norman]

Mark

Why not just lower the ways and fab a tailstock from concrete? seems like that would be a no brainer for you?

Dammit man! I had the same thought... I just might do that Gary! I have a few bags of 'crete left over, and I bet it would not be hard to do either.

[Travis R. Nelson]

Have you given any thought to casting a new concrete base? I would think a guy could attach a 2x4 inside the sonotube with a couple of 1-1/2" angles attached to the 2x. Remove the 2x and you have a nice clean metal lined grove. You could then use that as a "runner" for your tool rest and your tail stock to travel within. You could fab some type of clamp to go around to go around the concrete tube to hold those implements as well. Or you could even orient the angles as "tracks" and bolt or weld some heavy C channels on and clamp those fixtures onto them..Just a couple of thoughts.... Looks like you have the "foundations" of a good machine there...

[Tony Kahn]

So did we get any welding done this weekend?

[Mark Norman]

Nope, no welding this weekend Tony. Too much work around the house and indecision on my part as to how I want it all to go together from here. Gary's idea of lowering the ways and casting my own tailstock made for a few hours of pondering and puttering.
I had some walnut to cut up and seal as well.

Travis, I played with yer ideas in my head some but I just kept envisioning the 'channel' getting filled up with shavings and I dont want to have to re-cast the body at this point. I'll file the ideas away for future mods on a later model machine though.

As it turns out I have a defective chuck after all. The SN2 seems to be bulging out the back when I tighten it up and wont hold my work.

I need to spend a few hours cleaning up the shop but I keep putting more wood in there instead just making things worse.

I did fix my riding mower and have spent some time reducing the fuel around the property some so the fire marshal wont be giving me notice. A few hours with a weedwhacker as well.

Mark is tarred.. Any beer in this joint?

[Kim Ford]

Mark I would suggest having a clamp block machined that matches the contour of the rails. 2-3" long by the width determined by your spacing.