[dfro]

Photos of diy lathe #1:

Patterns:



Headstock, countershaft, lathe bed:





The bottom of the headstock:



I decided to put some old-school curves in the feet:





I filled the lathe bed's square steel tube with Commercial Grade Quikrete Fast-set Non-shrink Grout with a piece of rebar going down the middle.

I also used Bondo where the castings shrunk from the sand a little. I was going to paint it all green like the countershaft.

As I said before, I am going to move on to diy lathe attempt #2. What I plan to try with this lathe bed is to make it into a scraping reference plate. I will attach handles where I screwed in the feet. I have heard the advice that steel is not a good substance for making scraping references, because it twists as you take material off. Granite makes a great reference. So, I figure maybe by adding the non-shrinking grout, some of solid properties of stone will be gained. I figure it is worth a try. For almost no money, and some elbow grease, I could have a 36" flat reference to use in scraping mill and lathe ways. It has already been ground, so it is close to flat already.

Comments very welcome,

Dave

[S_J_H]

Dave,
Your method for the tailstock lock looks good. I would use the side clamp version. I think my idea will work very well though so I'll stick with it since the bed is already tapped. I'm using a 7/16" bolt which can create some serious clamping pressure!
Realistically the little tailstock will be the weakest link, not either of our clamping methods. I don't plan on doing a lot of tailstock supported work so unscrewing a bolt to position it won't be any bother to me.

I would probably go with the 10x22 lathe. It looks better made and heavier than the 9x19.
Thanks for the kind words on my mill and damper.
The dampers work ridiculously good. I can't say if bb's or lead shot would work as well. One thing is for certain. Resonance is gone completely.

I like your pics of DIY lathe#1. I see a nice machine as a possibilty there..
But I guess a nice long flat reference surface would be very nice to have as well.

Steve

[dfro]

Steve,

Thanks for the comments and advice.

In the future I would like to try the lost foam casting method. It really simplifies a lot of things. I like this primer on diy lost foam casting:

http://www.buildyouridea.com/foundry...oam_howto.html

I would like to build a cnc foam cutter. It could be a good first cnc project, since the mechanical parts do not have to be very rigid and the steppers can be small. It could be a good place to work out all of the electronics and software for the first time, too.

[dfro]

It has been way too long since my last post!

Since then, I have been following the thread on epoxy-granite and doing some of my own experiments:

http://www.cnczone.com/forums/showthread.php?t=30155

I think casting parts with e/g could be a very viable technique for anyone who wants to make small to medium sized machines that are massive, rigid, and accurate. People should be able to find most of the materials locally. It allows one to cold cast parts for machine tools as a replacement for cast iron. And, it is a room temperature process - no need to build a foundry and pour molten metal. These features are what made me seriously consider using e/g.

E/G is a moldable material made out of different sized aggregates, measured in certain ratios so that they pack together very tightly. The epoxy binds it all together. E/G is massive and it has 10 times the damping properties of iron. That means better surface finish on your parts and longer tool life. E/G can also approach the strength of aluminum. Adding steel reenforcement, like rebar, greatly increases its tensil strength.

I have built some small propane and electric foundries, and I have had a lot of fun casting aluminum parts. But, there is no way that I could cast in metal the kind of massive machine tool castings that I want to make. So, I am giving e/g a try.

***

I am now using epoxy-granite along with an old Atlas 6" lathe bed and a Chinese import headstock to build my cnc lathe. Not all of my experiments have been successful, as I will show everyone. Maybe you can learn from my mistakes, maybe you can give me some suggestions.

The first step was to build a vibrating table. The e/g mixture is thick like dough and will not flow if you don't vibrate it. Here are some pics of the table I built.





The next thing I needed was a table vibrator to cause the e/g mixture to settle in the mold. I decided to try and make a variable speed vibrator using a wood router, a router speed control, and an eccentric weight spinning in a wood box. I was able to make a few test samples of the e/g and make a few parts with this vibrator, but the bearings got extremely hot and started causing the wood to smoke. In the pictures bellow you can see I used brass bearings. BAD IDEA! I then replaced them with ball bearings, and I still had them getting too hot. I think this might work, if the whole thing was made out of aluminum and some special bearings were used. Here are two pics of the design. DO NOT COPY THIS DESIGN!!





My next try was to make a vibrator that runs on compressed air. I chose to make it out of steel tube, aluminum plate, e/g, and a steel ball. It is a simple design and a couple of these could be made very easily to shake the table. You do need a sufficient supply of compressed air or else they won't run for very long. Here is a link to a post on the e/g thread where I showed some pics of a cast aluminum vibrator I made several years ago:

http://www.cnczone.com/forums/showpo...postcount=2079

Here are some pics of the casting of my current compressed air vibrator:



After casting with e/g:



The compressed air spins a 1.625" steel ball around:



Flattening its top surface with a coat of table top epoxy:



I think one of these works pretty well at shaking my table. Two would work even better. With all the constructive and destructive interference of the two vibrators, you could really get some good chatter going. I think I would have to get a bigger air compressor, though.

My goal with the vibrator is to get the e/g to settle. While a few bubbles do rise to the surface of a casting and pop, there is no way of getting rid of most of the bubbles. It is way to thick.

If I make another of these in the future, I would make it round. I would have the inner steel tube, the hex bolts, and then an outer steel tube. A small amount of e/g would fill in between the tubes. That way, it would weigh a little less.

More pics later,

Dave

[dfro]

While the mathematical and materials science wizards on the e/g thread are working out the best e/g formula, I decided to settle on the basic formula that Cameron (ckelloug) created and posted. I think if I make the castings thick enough, and put some rebar or steel rod in them for tensile strength, I will be fine. Time and experience will tell. Here is Cameron's formula:

#6 Agsco Brown Aluminum Oxide = .18744
#4 Agsco Quartz = .38420
#2 Agsco Quartz = .12950
#2/0 Agsco Quartz = .11514
3M G800 Zeeospheres = .11352
3M G200 Zeeospheres = .07020

All the ratios by volume add up to 1.

I sourced all of the quartz aggregates of different sizes and found Zeeospheres and began making test samples. The epoxy is from US Composites - 635 low viscosity epoxy with the 2:1 ratio slow hardener. Here is how I calculate the mixture of the various aggregates:

http://www.cnczone.com/forums/showpo...postcount=3534

I created a spreadsheet to help me calculate how much aggregate and epoxy to measure. I start with the volume of e/g that I want and the spreadsheet calculates how much of each material I need to measure out in grams. This is a very handy tool.



Here are some pictures of me mixing the epoxy in by hand. I did vacuum degas the epoxy before adding it to the aggregate mixture. For my purposes and the relatively small volumes I am dealing with, mixing and squishing everything by hand is the best method. It works bubbles into the mix, but I am not that concerned about it. I am more concerned with making sure all the mix is wetted with the epoxy.







I settled on mixing in 20-22% epoxy by volume - I had trouble getting it to flow at a smaller ratio. I am going to try West Systems 105 resin with the slow hardener in future batches. I noticed that its viscosity was thinner than the US Composites epoxy - that means I can use a smaller percentage of the epoxy in the e/g mix.

After making some small square samples, I decided I was ready to infill a small 6" Atlas lathe bed with e/g. The ides was to take a cheap, thin walled lathe bed and turn it into a solid mass of iron and rock.

More pics later,
Dave

[RotarySMP]

I have read that playing a blow torch quickly over the surface bubbles pops them.

[dfro]

I have read that playing a blow torch quickly over the surface bubbles pops them.

Mark,

That works with straight epoxy with nothing added to it, like table top epoxy. You pour a 1/16" to 1/8" film and the blow torch causes the bubbles to expand and pop. But, with the e/g, it is so viscous and the castings are so thick that there is no way for the bubbles to get out. The stuff is like fresh asphalt when it is mixed and ready to be molded.

[dfro]

Here are some pictures of me infilling the Atlas lathe bed with e/g:



The lathe bed is clamped to the vibrating table and ready for the e/g. The springs under the top table are excellent at isolating the vibration from the workbench. I used my first vibrator to do this casting. I built a box that screws to the table. The vibrator is tipped vertically and screwed into the box, so that the vibration is along the horizontal plane.



I used copper tubing to keep the e/g away from the bolt holes in the bed that are for attaching the headstock.



A long shot of the casting. As the e/g is shook, it settles and gets a slight shiny sheen on top.



Later, I decided I wanted to permanently cast the feet into the lathe bed, so I had to extend the copper tubes.



Casting with the new and improved compressed air vibrator. It is very quiet compared to the wood router vibrator. Also, there are no shaft bearings and nothing gets hot - except maybe the air compressor motor. Air swirls around pushing the steel ball and eventually escapes out of the small hole in the center of the top plate.



The finished casting with some cosmetic filling of small gaps and some shaping. That bodifile with its holder is a great tool.

Thanks,
Dave

[RotarySMP]

Thanks for posting all those photos.

I really like your idea for the air driven vibrator. By varying the air flow can you change the frequency until the mix flows? There was a cool video on the main EG thread showing how a stiff mix went liquid when the right frequency was hit. Then the air should rise for the bubbles to be flamed off.

[dfro]

Mark,

Yes, the change in air pressure causes a change in frequency. I like the steel ball, because it vibrates slower than the router vibrator. I think the slower frequency is better at causing the e/g to settle. However, the vibration seems to work over a fairly wide frequency.

I took a test square (approx. 4x3x1.5") of some e/g that I cast to the shop of some friends. We put it in a 20 ton hydraulic press to see how much pressure it would take to break it. We had no measuring instruments to measure the pressure when it broke, but it went off like a gun shot!

That (unscientifically) confirmed to me that e/g is strong enough for my purposes, especially if I am going to cast some rebar in it to increase the strength.

Where the test sample cracked, there were small bubbles dispersed throughout it. E/G is just too thick to get all the bubbles out - it is 80% rock and dust. The only way I see to cast e/g with no bubbles is to mix and cast it in a vacuum.

The torch works great on table top epoxy. I used US Composites Kleer Kote Table Top Epoxy and a torch to cast the top surface of the e/g air vibrator.

Dave

[dfro]

Next is the headstock. I bought a generic import headstock and spindle for a 7x12 lathe from Little Machine Shop. I also got tapered bearings for it. I wanted to make it taller, but instead of buying a cast iron riser block or making my own, I decided to try e/g again. The first thing I did was to cut a steel tube and glue it inside the headstock. This keeps the e/g away from where the spindle needs to go. I also had to drill and tap a fourth hole on the bottom for attaching bolts. Are these headstocks attached on these 7x12's with only three bolts? If so, I do not see how anybody can get any kind of accuracy out of machines made with these headstocks.

The goal here is again to turn a cheap, thin walled casting into a solid mass of iron and rock.



Headstock with bolts to key into the e/g.



Mold with coupling nuts and hex bolts. These will be the attachment points for the headstock to be bolted to the lathe bed.



Ready for casting. Steel rings and transmits vibration, so the bolts are not touching.



Casting the e/g.



Demolding. I did not use a very good release agent - car wax. I planned to destroy the mold anyway.



I leveled the front of the headstock and cast a coat of table top epoxy to smooth the front face. I made walls around the perimeter with tape. Do not use electric tape if you are going to pass a torch over the epoxy, use masking tape. The electric tape started to shrink and I had to use molding clay to try to stop it from leaking!



The finished headstock casting with some cosmetic fill and sanding. Notice the steel tube I glued inside it.



Headstock with spindle - rear view



With spindle - front view. This thing is really solid and heavy.

Thanks,
Dave

[will gilmore]

Head stock looks awesome. I could have done something similar and saved myself some money and machining time. how do you plan to align the axis of the spindle to the ways? shims?

[brunog]

Nice work Dave,
If you are thinking of making a thinner mix next time, why not try the table top epoxy?

The product is thinner, unless there is a cost issue, it just might be the solution for a thinner mix.

Best regards,

Bruno

[ckelloug]

Dave,

Congratulations for actually getting something done. Fabulous work I might add.

You mentioned release agents so I'll provide a quick comment:

Have a look at Mann Easy Release 200. At $11.00 a can, it cant be much more expensive than car wax. I've been using it for test specimens. It leaves a satin finish but in a polished steel specimen mold, I got an epoxy impression so accurate as to be able to see .0005 inch or less imperfections in the surface grinder finish after the thing was lapped to 3000 grit diamond.



--Cameron

[RotarySMP]

Nice work on that head stock rise! I have a 7x12 which I CNC'd and the 3 three bolt interface to the bed is the least of these machines worries.

I was really surprised that mine has a very accurate headstock alignment (could be a fluke). The tail stock is the real turd!

http://www.wrathall.com/Interests/ma...ent_check1.htm

[dfro]

Thanks guys for the kind words.

will,
I have recently noticed your 'Granite surface plate lathe' thread. Your progress looks great! That is going to be a monster lathe! I also just checked out your www.gothamchopshop.com website - very cool work. I have been fascinated with metal forming work. I got several of Kent White's videos at http://www.tinmantech.com. I learned a lot from them and got a lot of ideas. He is a real artist. I play saxophone, and, at some point, I would like to fabricate my own custom tenor saxophone neck out of brass sheet. That project is way on the back burner for now, though.

As far as aligning the headstock, I am not completely happy with how I have done it. After casting the headstock and the lathe bed, I made a series of time consuming mistakes that I will share with everyone, later. I hope others can learn from it and that I can get some advice from people. The alignment of the headstock is included in those mistakes.

What I plan to do is a fix for something I could have easily included in the e/g headstock casting. I am going to make two 1/8" or 1/4" thick steel strips that are the width of the bed ways and sized to be glued to the underside of the headstock with a toughened epoxy like 'jb weld'. They will each have two holes in them, so that the clamping bolts can reach the four coupling nuts that are cast into the headstock. I will roughen the glue side of the steel strips, and scrape the bottom surfaces that will contact the ways. I will also plug the headstock's coupling nuts with modeling clay to keep the glue from getting in the threads. I will then glue the strips to the bottom of the headstock, clear away any squeeze out, turn it rightside up, and place it on one of my surface plates (the glue is still wet at this point). Beforehand, I will wipe some blue spotting paint on the surface plate to protect the plate from any stray epoxy.

Next, I will knock and tap the headstock to get the front surface of the spindle to line up perfectly square with a machinist square that is placed next to the headstock on the surface plate. This is all by eye, but I think I will get close. Then, once the 'jb weld' has cured, I will mark the lathe bed with 'hi-spot' blue paint and scrape the headstock into the ways. Maybe I will have to shim, eventually - we'll see.

I think, in this case, the 'jb weld' is kind of like a poor man's Moglice. Here is a quote from the Moglice site:

"Molding to fit precision: The molding process gives a full surface contact even given irregular shapes and angles. This eliminates the need for costly match machining of parts."

Come to think of it, this method might be easier than casting the steel strips into the headstock. I am liking this idea.

Bruno,
It is my recollection that the US Composites - 635 low viscosity epoxy with the 2:1 ratio slow hardener is thinner than the US Composites table top epoxy. I could be wrong, though. I definitely know that the West Systems 150 with the slow hardener is thinner than the Kleer Kote table top epoxy. I will explain how I know that, later. It's not pretty.

Cameron,
Thanks for the advice on the release agent. I will get some. I know you guys worked that out somewhere in the e/g thread, but at the time I didn't feel like digging for it.

And, thank you for your efforts in producing the e/g formula that I am now using. I wouldn't be trying this without you and the other contributers to the e/g thread sharing your work!

Mark,
I enjoyed browsing your site. There is a lot to learn there.
You might want to get a spare tailstock at Little Machine Shop and do an alignment trick with toughened epoxy, like what I am thinking of doing with my headstock. Find some way of having a film of epoxy between two parts of the tailstock (grind away some iron between the two castings). You could chuck a precision ground rod in the headstock chuck and also the tailstock. Then, clamp and knock and adjust the tailstock until a dial test indicator shows that the rod is perfectly aligned along the length of the lathe bed - top and side. When the 'jb weld' cures unclamp everything and clean it up with a file. You could even drill and tap some screw holes in the bottom to hold the two pieces together, if you are afraid of the glue breaking. I don't think it will, though.

I am thinking of doing something along those lines for the tailstock on my lathe.
It might be worth trying.

Thanks,
Dave

[will gilmore]

Sounds like you have a good plan for headstock alignment. I'm a bit worried about it on my lathe. Scraping is my last resort. I'm hoping that it magically falls into alignment (I used stacked ground plate for my spacer).

Keep it up! I'm really impressed by your work in this thread.

[RotarySMP]

I was thinking of doing something like what you suggest with the tailstock, but haven't yet, cause it would seem like investing time polishing a turd

The foot is so badly machined and scraped, and the joint between the foot and the other casting so lacking in perpendicular surfaces, that I really don't see it being a great starting point. On top of that the alignment changes measurable between the ram locked and ram unlocked.

A CNC lathe doesn't need a set over tailstock, so I would rather start with a block of cast iron, and machine and scrape the base properly, and then set it up to slide on the bed, driven by the saddle. Then with a boring bar between centers on the existing tailstock, the new tailstock could be bored true to the bed.

Actually what is more likely is that I finally move out of the apartment into a house, and buy a 12x36!

[dfro]

I was thinking of doing something like what you suggest with the tailstock, but haven't yet, cause it would seem like investing time polishing a turd

I hear you. I am doing the DIY route, so that I can control the quality of my machine. I want modular components that can be replaced from several sources. And, with e/g, I can make the castings I need for it.

Maybe you could make an e/g tailstock for your lathe to practice casting. You could bore a better housing for your tailstock quill out of steel rod, make a steel base to travel on the ways, then find some way to mold it all together with e/g. Might be fun.

Thanks,
Dave

[RotarySMP]

It is tempting...