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

  1. #1
    Join Date
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    Making plans to build a concrete bowl lathe - opinions welcome.

    My original intention was to have a friend help me fabricate a bowl lathe using some scrap steel he/we have laying around. I posted here a request for a spindle to use for the project. I got a lot of helpful responses and one of them mentioned using concrete as a base material...As it turns out I have extensive experience with precast concrete. It is an awesome building material.

    That got me thinking and I sketched up my thoughts on paper.. I calculated the weight at almost 1000# with the motor and steel bed.



    I plan on using a three horse three phase motor with variable speed control.

    I still have not finalised the design of the headstock configuration, I wont until I have the spindle, pulley and motor in hand.

    I planed on fabricating steel ways out of 3" or 4" square steel stock that will adjust vertically by bolting to some uni-strut embedded vertically into the concrete. The motor will also hang from embedded uni-strut.

    I think if it is planned well with the uni-strut strategically located I would have a multitude of options for mounting up various fabricated tool rests.

    What to consider??? I think the building of the concrete formwork will be a fun project in itself.

    Any input is welcome.

    I'm glad I found this site, there seems to be some real helpful, friendly and talented people her.. I think I'll hang around for a while.

    Thanks in advance,
    Mark
    Last edited by Mark Norman; 03-07-2009 at 6:46 PM.

  2. #2
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    Mark, dont see why it wouldnt work..I would make the body out of concrete but I would make the headstock out of 8X8 steel so would have a place to mount and/or replace the spindle bearings..but you could fill the steel tubing also.....this should be interesting
    Dave

    IN GOD WE TRUST
    USN Retired

  3. #3
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    Should be technically feasible. Many things to consider as you get further into the project. One might be location.
    Richard in Wimberley

  4. #4
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    Thanks Dave

    The spindle bearings are whats giving me a hard time conceptualising. Until I have a spindle in hand I'm not sure what the outcome will ultimatly be. The structural steel box tubing is an option depending what I can find. Two pieces of heavy channel or the like may fit the bill as well.

    Richard, I have a location in my shop for it and an overhead trolly crane too so casing it upside down or laying on its face is the method of choice here. I plan on using a melamine veneer for the formwork so I will end up with a very smooth surface finish...

    I am determined to make it happen. I'll get pics along the way too

    Here is a concrete shower I made for the hot tub patio a few yars back. Turned out real nice...Dont ask about "the rest of the story" I forgot to drain it one winter and the pipes inside froze and now it leaks all over..


  5. #5
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    This will be a very interesting topic, we all would love to see the process and with it pictures. GL

  6. #6
    You might consider buying a stock spindle assembly from Powermatic...the ones they use for 3520b. They come with indexing holes, bearings and threaded end with #2MT. Once you had it in hand, you could design your support frame for it.

  7. #7
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    I have a line on a Vicmarc 300 spindle

    From a member here.
    Like this:



    How to embed bearing race holders into the head will be a challenge. As will the pulley and drive belt. If the belt is to be between the bearings it will make it more practical to use steel for the headstock. We will see...and I love pics
    Last edited by Mark Norman; 03-07-2009 at 9:03 PM.

  8. #8
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    Dec 2008
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    Quote Originally Posted by Mark Norman View Post
    From a member here.
    Like this:



    How to embed bearing race holders into the head will be a challenge. As will the pulley and drive belt. If the belt is to be between the bearings it will make it more practical to use steel for the headstock. We will see...and I love pics
    Mark, I made a spindle holder (for a different project ) and to hold the bearings I got a piece of pipe, made it fit the outside of the bearing race, cut it off about 3/4" and tack welded to the frame them slid bearings in and then slid spindle through..( easier said than typed )
    Dave

    IN GOD WE TRUST
    USN Retired

  9. #9
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    Ivy, VA
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    Quote Originally Posted by Mark Norman View Post
    My original intention was to have a friend help me fabricate a bowl lathe using some scrap steel he/we have laying around. I posted here a request for a spindle to use for the project. I got a lot of helpful responses and one of them mentioned using concrete as a base material...As it turns out I have extensive experience with precast concrete. It is an awesome building material.

    That got me thinking and I sketched up my thoughts on paper.. I calculated the weight at almost 1000# with the motor and steel bed.



    I plan on using a three horse three phase motor with variable speed control.

    I still have not finalised the design of the headstock configuration, I wont until I have the spindle, pulley and motor in hand.

    I planed on fabricating steel ways out of 3" or 4" square steel stock that will adjust vertically by bolting to some uni-strut embedded vertically into the concrete. The motor will also hang from embedded uni-strut.

    I think if it is planned well with the uni-strut strategically located I would have a multitude of options for mounting up various fabricated tool rests.

    What to consider??? I think the building of the concrete formwork will be a fun project in itself.

    Any input is welcome.

    I'm glad I found this site, there seems to be some real helpful, friendly and talented people her.. I think I'll hang around for a while.

    Thanks in advance,
    Mark

    Since its purely concept at this stage, I'd seriously consider increasing the footprint width to 30" or even more. I've heard Fred say over and over that the triangulation of the weight is the most important thing in making it rocksolid steady. That way an out of balance blank has to lift much more weight to rock the lathe---a 30" lever vs. 20". I wouldn't have thought it much difference, but he said it would move all over with narrower legs on it. Just a suggestion. I figure every detail matters at this point. I'm eager to see how it goes!! If I had the time to devote to it (I work 30+ hrs at night, and am turning almost full time as well) I would've done the same thing for a mega-bowl lathe. I'd even thought about using pieces of inverted railroad rail as the ways, and have them machined dead flat. My family has a farm that the railroad bisects--there are short pieces of rail that end up in the river all the time.

  10. #10
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    Holly Springs NC
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    If you incorporated the idea of a shower into the lathe, maybe on the outboard side of the headstock, well then, you would have something truly unique!

    Seriously, though - after having just finished my build, I'm really looking forward to watching your journey. The idea of a concrete is just fascinating to me. Best of luck.

  11. #11
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    Nov 2008
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    Redford, MI
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    As David says, a tubular spindle carrier would be relatively easy to fabricate. I would suggest using "Round Mechanical Tubing" rather than pipe. RMT can be purchased in a variety of ODxID combinations that will reduce the amount of machining necessary to mount the bearings and it's much closer to round than pipe. Carry on.

  12. #12
    Dang, this almost makes me want to take up concrete work again. I did high end residential work for too many years, and got to form up a lot of interesting stuff. I don't know that I would want the headstock part made out of concrete, but could easily see making a bed/frame for the metal out of concrete. Excellent at shock absorption. I would make the bed more like a standard lathe (big I beam with arched feet on either end), rather than a box because you will want to stand close to the lathe, and be able to get your feet in close to the work so you never have to bend over. Will you ever need to move the lathe, or are you going to put it in one place for ever? Pouring level on site is easy, otherwise, you will need levelers. Metal inbeds with drilled and plug welded anchors on them for holding the bed and headstock in place. You can also bend plywood for the curves, and wrap the pieces in the thin painters plastic or 2 mil plastic (staple or tape into place), and get the same smooth finish, and do use a vibrator. Probably some 3/8 rebar bent to shape. Sounds fun.
    robo hippy

  13. #13
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    Thanks for all the replies

    Some good thing to consider posted here... and I will.

    The drawing is rough but I did consider being able to stand close to the work. I actually have reliefs in the base as a sort of toe space so I could get right up to it with my knees touching the body of the lathe. I will likely make it wider than the 20" shown also.

    As for leveling it, I will just use grout under the 'feet'. It wont ever move once I get it in place.

    As for the bearing holders in the headstock, I will look into using the round tubing. I'm sketching up some details of the headstock that will accommodate the pulleys between the bearings. Two pieces of 1' x 4" steel box tubing with holes drilled in and round stock welded in place to receive the bearing races. The critical part will be making sure they are absolutely parallel.

    Thanks again, i will keep you all posted.

  14. #14
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    Mark,
    You should be able to align your bearing housings by assembling the set-up with a dummy shaft and bearings. That way you are assured of alignment, provided you do the welding properly.

  15. #15
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    I'm sure I could Ron

    Thanks for the input!
    I'm still thinking of using pillow block bearings for the spindle. I'm not sure I like the idea of having the pulleys between the bearings. Having the pulleys outboard will make not only the fabrication much easier but changing the belt on the pulleys would be simple. I could also put a much bigger pulley on for real slow turning of big out of balance pieces.

    I was looking around the net and found a BIG home made bowl lathe. :
    http://www.proserpinewoodturners.com/The_Big_Bowl.html

    Now thats impressive!!!

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