[RotarySMP]

I have been havesting E-Bay for the last couple of years, with the intention of making a small mineral epoxy framed gantry mill.

I have:
4x 340mm HSR15's (dual blocks per rail)
2x 280mm HSR20 (single long block per rail)
3x ground C2 ballscrews (each about 300mm or a little longer)
3x Yaskawa 60W 24V servos
3 axis CNCDrives.com UServo + backplane/breakout board
24V Chinese switching PSU.

I have been mucking around designing the Mineral Epoxy bed, but don't have the equipment to mill it yet.

Thats why I have decided to bodge up the machine with an MDF frame to get started, and get some experience. I can then recycle all the hardware onto the rigid frame in the future.

[RotarySMP]

I normally get pretty myself tied in knots at the design phase, and decided this time to just wing it.

On the spare of the moment, I did this design work:



then headed of the hardware store and got them to cut the pieces of MDF:


Got back and realised my first mistake. For some reason I'd designed 450mm long for the bed, but the rails are only 340mm long.

[RotarySMP]

John (Microcarve) has a great way of tying the MDF sides together with threaded rod - puting the MDF under compression, so I am copying that. His thread is excellent. Thanks for sharing all that experience John.
http://www.cnczone.com/forums/807735-post31.html



This was routed with a little Proxxon ID/E - Pretty cool tool.
PROXXON - IB/E

[RotarySMP]

Along the way I started to model the mill. The model is not yet finished. The initial spindle will me my Proxxon Collet spindle http://www.cnczone.com/forums/vertic...pindles-4.html



I have an old Deckel engraver frame with a Sherline spindle mounted on it. It is in a friends garage an hour form home.
wrathall.com

After gluing the spacer strips on the bed (and cutting the extra 100mm back off), I used Frankendeckel to drill the rail mounting holes (well 5 out of 6 on each side, as it needed 300mm of travel an FD only has 298mm in X) The last hole was drilled using the rail as a jig.



The back got relieved a little to countersink the rail mount nuts.

[RotarySMP]

While out at FrankenDeckel, I also drilled the table for the Y rail block mounting holes.
The big holes were for mounting on a lathe cross slide. I turned up some cast iron plugs for the top and epoxied them in, then flycut them back. Looks like FD is a bit out of tram, as on one of the four the fly cutter started to rub the table.

[RotarySMP]

When I modelled the Y Rails, I could no longer remember my login for THK, so instead of downloading thier 3D models, I just bodged up simple blocks and rails. Unfortunately, I forgot to model the blocks plastic end caps (which have the ball return circuits).

This LH block has a screw through the table to locate it.


The second block sticks out about 4.5mm due to the end cap, so the screw holes don't align.


I made the screw holes nicely centered in the edge T-slots...


... rather than measuring the blocks!


I guess I'll use this table eventually as a raised table on a future mill, and buy another one for this project.

[RotarySMP]

The only other job I have done so far is to cut out an oval for the Y motor to fit through, and allow belt tensioning.



I want the PSU, and servo driver to live under the table, keeping the machine compact.

I'm going to busy for the next month or so, but lucky this project is currently very portable.

[asuratman]

Is that mdf rigid enough to withstand cutting force?

[RotarySMP]

Depends what you are cutting, how deep and how fast. I expect it to work fine with small mills (the spindle only takes mills up to 1/8" - 3.2mm).

I do not expect to be able to mill steel on it with this frame.

[RotarySMP]

I need some 6mm Alloy plate to mount the motors. Decided just to make some. Only took me 01:10, including set up and clean up. I couldn't drive to metalsupermarket and back in that time (especially as they are closed on a sunday).



Heavy shrinkage on a part like this...


Lucky I used long risers...


Since I need to machine it anyway, I just used a scrap of plywood as a pattern, and didn't bother to put any draft on the edges. Of course it didn't pull cleanly, so there is a lot of flashing.

[pete from TN]

That is pretty damn cool man. Honestly I have watched that fellows router build and it is impressive to say the least. His design can actually rout aluminum as several of his customers have done so. The design is very well thought out and also IMHO elegant. I gotta wonder if a small CNC mill could not be made using MDF and epoxy laminating multiple layers of MDF with pressure. Surely with say eight or ten pieces of MDF cut to shape and epoxied together then sealed to keep it from absorbing fluids would result in a very rigid structure. It would also be pretty cheap to make. I know when I was a PRo-woodworker we often used epoxy to glue up IPE wood or ironwood and that was mostly because it was too dense for typical wood glues to adequately absorb into it. The Epoxy made for a super rigid structure and I know where there are about ten outdoor benches made from this stuff that are built using a stacked alternating plate design of layers and quite honestly you could probably park an M1 tank on top and it would not fold. There is also some definite vibration absorbtion qualities with MDF that can make for a useful machine base. Something the size of say an X2 could probably be made pretty easily and perform reasonably well using the same fastening properties he is using and say this laminating setup.

What kinda furnace do you use to melt the aluminum? It looks like a pretty big part but pics can be deceiving... How much material can you get to liquify with your setup. That is something I have ALWAYS been interested in but I am not sure I have the balls to play with molten metal around the house like that...peace

Pete

[RotarySMP]

It is only a little A5 sized furnace. I slightly scaled down the version in Anon's book Foundry Tutorial Book

Mine was built into an old 20L oil drum.


Have you checked out Jerry's Bamboo Router?
http://www.cnczone.com/forums/cnc_wo...w_machine.html

He has a comparison of the engineering properties of Bamboo vrs MDF about 2/3 the way through.

[SCzEngrgGroup]

I'm very curious about that casting you did - Is that 6061? Did you start with chips? I'd always heard you really couldn't cast 6061 chips, because you'd end up with too much slag. I generate a huge quantity of chips (I have 5 garbage cans full sitting in the shop right now, from just a few days of work), and I'd love to be able to do something more useful with them than just dropping them at the recyclers.

Regards,
Ray L.

[RotarySMP]

I don't know what flavour of Scrapiminium it is. It was some telephone transformer covers. Has a lot of silicon in it and doesn't machine well, certainly not 6061.

If you melt down swarf, you'll get a lot of dross to skim off. Even melting down the thin wall transformer covers I get probably 1/8 dross by volume. When you remelt from ingots, you get much cleaner metal.

[SCzEngrgGroup]

I don't know what flavour of Scrapiminium it is. It was some telephone transformer covers. Has a lot of silicon in it and doesn't machine well, certainly not 6061.

If you melt down swarf, you'll get a lot of dross to skim off. Even melting down the thin wall transformer covers I get probably 1/8 dross by volume. When you remelt from ingots, you get much cleaner metal.

So I'm guessing those were cast covers, which would make them a casting-friendly material?

Regards,
Ray L.

[RotarySMP]

Correct. The best casting scrap are automotive cast parts (A356 alloy)?

[CNCfun&games]

Mark,

Very creative Design and use of materials!
Keep the pictures coming.

I'm sure you are generating a lot of interest.

W. Smith, Mission Viejo, CA
http://www.cnczone.com/forums/bencht...including.html

[RotarySMP]

Thanks for the encouragement.

Today I turned down a piece of that cast plate and made the Y motor mount. This is the worst machining aluminium I have ever had. Gums up the tool edge regardless of speed or cutting oil. The bore looks bad in the photo, but that is just because one side is polished from fitting the motor (it is a pretty close fit.)

To drill the motor holes, I used peice of tool steel between the bed and the four jaw chuck as a primitive indexer, and drilled with the Proxxon mounted on a tool holder.

I ended up lacking edge distance on the original holes to mount this plate to the MDF, so I drilled four more further out.



The slots were just filed. This thing would have been a lot easier to make on a small aluminium cutting gantry mill

[RotarySMP]

Any of your other guys rotate between hobbies? I do. Between machining (includes casting), guitar, and photography. I played guitar really intensively in spring, then I bought a Leica M8 at the start of summer, so did nothing on my little mill project till last weekend.

At this rate it will take me about another 100 years.

I mounted the side panels.

[wizard]

I use to run around with an RZ67 but eventually got rid of that camera. Feeding it film and buying lenses was and probably still is more expensive than buying machine tools. My guitar adventures are to embarrassing to talk about!

Hey maybe you will make progress again now that you are back.

Any of your other guys rotate between hobbies? I do. Between machining (includes casting), guitar, and photography. I played guitar really intensively in spring, then I bought a Leica M8 at the start of summer, so did nothing on my little mill project till last weekend.

At this rate it will take me about another 100 years.

I mounted the side panels.