Concrete Lathe Adventure

[Tom Dunn AL]

Hi, guys,
Sorry to have been away for a bit, but life has its duties... In this case, a new 26'x14' treated wood deck... I am still scratching my head as to what I would like to do... Progress has been made with gathering scrap wood to build the form, thanks to the deck project. Also, my brother has been enlisted to help me fashion a temporary pulley from MDF. He builds HiFi speakers, so he is skilled, and equipped, to cut precise rounds out of MDF.

[Steve Kubien]

Tom, I just caught this thread and skimming the comments, my observation was not addressed... The angle iron from any bed frame I have ever seen is not thick enough to act as the ways of your lathe. It will flex so much that the vibration will (just a guess) make it impossible to get a clean cut. Sure, the concrete will absorb a lot of vibration but it will not be able to stop it between the ways, up to your tool rest.

If this has been addressed and I missed it, I apologize.

[Doug Herzberg]

Tom, I just caught this thread and skimming the comments, my observation was not addressed... The angle iron from any bed frame I have ever seen is not thick enough to act as the ways of your lathe. It will flex so much that the vibration will (just a guess) make it impossible to get a clean cut. Sure, the concrete will absorb a lot of vibration but it will not be able to stop it between the ways, up to your tool rest.

If this has been addressed and I missed it, I apologize.

Think RR rail stock or I-Beams like they use in framing houses - maybe a cutoff? Just my $.02.

[Tom Dunn AL]

Hi, Steve and Doug,
Thanks for jumping in... Steve, various folks have pointed out the need for a better bed/ways. I apologize for not addressing you directly. I am still exploring designs, but I like the idea of incorporating the ways into the bed. Basically, the bed iron is used to wrap the corners of the bed "legs". This improves rigidity, but doesn't do much to improve accuracy. I am also considering just using this design for a wood lathe. I do have a friend that works for the railroad and I am going to see if he can get me some track. I would still have the task of developing ways.

Thanks! Keep the suggestions coming!

[Rick Markham]

I think dealing with RR track is going to be a task itself. I'd be inclined to go to the local scrap yard and look for something with a little more workability. Pretty sure beyond the extreme weight of the rail stock itself, it's going to be incredibly hard to cut. I don't know for sure, but my suspicion is that rail stock is probably hardened, in which case you are going to have to anneal it before you can cut it. (Maybe someone here knows for sure) You have to consider that it was created with the purpose of supporting several million tons moving at high speed on a regualar basis (On hardened steel wheels) for many many years. I doubt it's very workable. (Like I said this is all conjecture on my part.) At the very least even if it isn't hardened when it's made, then a used piece of rail track is certainly going to have an extensive amount of work hardening due to the years of trains travelling over it.

[Tom Dunn AL]

I think dealing with RR track is going to be a task itself. I'd be inclined to go to the local scrap yard and look for something with a little more workability. Pretty sure beyond the extreme weight of the rail stock itself, it's going to be incredibly hard to cut. I don't know for sure, but my suspicion is that rail stock is probably hardened, in which case you are going to have to anneal it before you can cut it. (Maybe someone here knows for sure) You have to consider that it was created with the purpose of supporting several million tons moving at high speed on a regualar basis (On hardened steel wheels) for many many years. I doubt it's very workable. (Like I said this is all conjecture on my part.) At the very least even if it isn't hardened when it's made, then a used piece of rail track is certainly going to have an extensive amount of work hardening due to the years of trains travelling over it.

Hi, Rick... and thanks! Yes, there are DIY bowl lathes out there using RR track. But, not much direction on how it was accomplished. And, 100% metal.

I think I have honed in on a Bench Top Wood Lathe design that I can live with as a first attempt [thanks to Anon's napkin idea on my sister thread at alloyavenue.com.] Here's the sketch:

[Tom Dunn AL]

Progress includes removing the lug bolts from the hub... Measuring the lugs - 1/2"... Measuring the hub... And, creating a hub template on OpenOffice/Draw to layout the head stock boards... I am thinking I will use 5000# PSI concrete...

[Rick Markham]

Tom, if there are guys using Railroad tracks then it's possible. I'd say stick with that if it works, heck you won't get any deflection in the ways! If it were me, I'd go for Big. But I tend to go overboard on things! (I don't like making things twice either)

[ray hampton]

a railroad track are only HEAVY on the top, the bottom section of the track are about 1/2 inch or 1 inch thick shape like a upside down T , cut the top off and weld two bottom sections together, another method will require three sections of tracks, weld one track between the bottom of the other two tracks

[Tom Dunn AL]

Rick and Ray,
Thanks for contributing! I have spoken with my RR contact and he is going to look for some. In the meantime, I am going to forge ahead on the smaller scale.

A little more progress.
Rough Draft of General Layout of Cuts.
Efficency of materials layout sacrificed to obtain maximum factory board edges for trueness.
Pour will be made into the inverted lathe mold to allow maximum smoothness of bed leg tops and leveling of bottom of lathe.
Head stock and bed leg pours will each be another box within the main box.
Head stock dog ears will be accomplished with triangular bracing cut from sufficient solid board stock.
Form bracing and rebar to be added.
I note that I have a few errors to clean up... But, now, it has gotten late...

[Rick Markham]

Tom, speaking of Railroad stuff... I was doing some research trying to find any pictures of people using track for ways, I didn't find any. (If anyone has pictures, I'd be interested in seeing one) but I came across Pre stressed concrete RR ties. It might be something worth looking into, you could avoid building a bed yourself completely. Attach your Ways to the the tie where the track is fastened. If you think about it, other than having to blow chips out from under the ways (If you suspended them above it would allow the shavings space to be easily blown out and not compact) It's actually a pretty simple solution to a complex problem, The fasteners are built to be exactly the same height, etc. (Tight tolerances) If you did an accurate job of attaching the ways you'd be golden. You won't ever have to worry about the thing flexing (Assuming you support the length of the tie, maybe the a RR track running as a spine under it) you build some legs, headstock, tailstock, and your in business. (that's the easy part right ) Here's the linky to the ties http://www.roclatie.com/ (I'm not affiliated with them, nor have I even seen one)

[Tom Dunn AL]

Rick,
Interesting site... That's a very creative solution... If I were building up a large lathe, that might be the way to go... Great idea!

[ray hampton]

A rail road track will work but you can buy smaller tracks, overhead heists or cranes use a lighter track

[Jeff Nicol]

Well It has been a while since I have had time to check in on the Creek and this thread is right up my alley, but I would have to do some redesigning of the headstock before doing anything. First if you have enough length on the axle I would mount the hub on the opposite end away from the ways of the lathe. To do this correctly you would need to run a pipe through the concrete that the spindle would go through with a mounting plate welded on each end for attaching another bearing on the spindle side to support it. Part of this would be to make the form to allow the pulley in the center of the headstock, this would be done with the pipe I mentioned earlier it would be made in 2 sections with the steel plates on each end. The plates in the center where the pulley will be would be used as part of the form, and rebar would be able to be welded between them and a cage would be created to continue rebar through out the headstock. This allows for the pulley and belt to be out of the way of the work area and the replacement of bearings, pulley etc would be made fairly easy. Also then you will be able to alighn the spindle with the ways very easily too.

As for the train rail for the ways, the "T" portion would be used as the ways as they are roughly 5/8" thick and width is determined on rail size. When you figure out the distance you want the "Gap" to be in the ways, a portion of the rails could be cut off so as to make the bed roughly 8" wide and the heavy tops would make excelent weight for lathe stability. I know this may seem like a lot of work, but in the long run you would have a very servicable lathe that would last a long time. I will draw up a quick sketch and post it in a little bit to give you some more insight to my over active mind!

Jeff


Here is the little sketch that if quick and rough, but it should give you an idea what I mean. The squiggly lines in the side view are rebar and in the top view you can see a little more what I mean. I would maybe instead of re-bar on the through tubes I would put 4 pieces of pipe either 3/4" or 1" black iron pipe that would be placed in areas that you could drill and tap mounting holes for the bearing in front and the spindle hub in back. I guess I would take the whole axle to a machine shop and have the nose threads turned, maybe an aditional collar made true to the spindle to add more surface area for the chucks and faceplates to mount to. Also I would have them put a groove for a woodruf key that the pulley would slide onto and the set screw would tighten into place on.

I get a little over the top on explanations but hope this helps,

Jeff

[Tom Dunn AL]

Thanks, Ray and Jeff!

Great input Jeff and thank you for the effort of sketching the design. I like the way you set up the groove for the pulley belt. Good thinking...

There has been lots of observation by many that a pulley centered between the bearings would be a superior design; I agree completely. My choice of hub and axle was based purely on economics. I did check on spindle and bearing prices before making my purchase. Best I could tell, I was looking at several hundreds of dollars, plus machining. I chose the trailer hub approach, only after seeing an operational unit and reading discussions of the sufficiency of the design to manage the high lateral loads of turning. I do not know the outcome of this prototype, but I am enjoying the adventure of working through design and assembly. Wheel hubs off the front end of automobiles have also been used.

Today's progress has just been in doing a little poking around with the supplies I have and mentally working through the assembly to find problems. One issues I was having was how to box off the recess for the hub in the head stock. It was really taxing me, until I realized that the hub came in a plastic container that could easily be cut down to box the recess. The container even has tangs that will make it easy to attach it to the head stock mold. I also re-drew my parts layout to fit on the two half-sheets (48"x44") of plywood that I have on hand.

One thing that I am searching for is information on is how to cut the woodruf key way with just hand tools. I am seeing that it has been routinely done by others, but I have not seen a procedure that I think suits me. Any suggestions would be welcomed. It also occurs to me that, since I will cast all the parts, I do not have to use the attachment methods that manufacturers use. If it is easier to file the end of the spindle into a square and cast the inside of the chuck plate bore to match it, maybe that kind of thinking has merit. Thoughts?

Thanks for taking this journey with me!