[mamexp]

Hi all,

I've been a lurker for a while to learn more about CNC in general. I've been thinking of getting a small CNC (12" x 24" x 3-4" ) to do mostly aluminum ( up to 1 " thick) and HDPE.

I havent found one that suits my need (either too big and expensive or too small). So i'm thinking of build my own. Any ideas are welcome,

If i buy aluminum stocks (flat bar) from Online metals or Metal supermarkets, do i need to debur or resurface for flatness?

If so, i guess i will have to ban the DIY idea because i dont have access to a mill machine.

Ps. I'm from Toronto, Canada. Where do i get metals for a good price?

[jharvey407]

If i buy aluminum stocks (flat bar) from Online metals or Metal supermarkets, do i need to debur or resurface for flatness?

I have not purchased online, I get my aluminum from a local supplier.

It is not flat. It's flat enough for typical fabrication, but not for the accuracy you are going to need for a CNC machine.

I only need to deburr the cut ends.

Have you considered aluminum extrusions from a supplier like Bosch, or 8020?

[ger21]

If you want flat aluminum, you need to buy cast tooling plate. It's ground flat.

Mic-6 is one name for it. I've bought mine on Ebay.

[mamexp]

If you want flat aluminum, you need to buy cast tooling plate. It's ground flat.

Mic-6 is one name for it. I've bought mine on Ebay.

oh MIC-6 ? I've seen that grade name but dont understand what i means. Is it still 6061-t6 alloy?

I got a PM that says its best to get from local to make sure the flat is processed as i requires. Is buying online risky then?

I've considered extruded bar like 8020 but i read somewhere that they're also not flat enough (i believe i read in a build thread where the author was using it to support a linear rail)

I really think 8020 is the best way for me if i cant get aluminum flat bars machined for a reasonable price.

[LazyMan]

.This is direct from Alcoa below. Its not 6061-t6 alloy neither is it extruded. It's cast and machined flat and stays that way when -machined because it has minimal residual stresses. MIC 6 or tool and jig plate (generic name) is not ideal for use in applications that need high strength though. I used MIC-6 for my first machine and it was joy to work with. As for flat 6061 flat stock, it does not matter where you order it from, its just not very flat. I can be flat enough for many applications but if you need a very flat, you will be disappointed.

MIC 6® Aluminum Cast Plate

The Best of the Best
MIC 6® Aluminum Cast Plate is a blend of the most desirable features of many individual metals. The result is a cast aluminum plate that meets the challenge of product accuracy demanded by today's industry.

Because of its cast granular structure and stress relieving properties, MIC 6® Aluminum Cast Plate allows high-speed metal removal with little, if any, of the distortion commonly inherent in long grained wrought, flat-rolled metals.

Using proper aluminum machining methods, tolerances in the thousandths can be consistently maintained. MIC 6® Aluminum Cast Plate is finished to 20 microinches typical on both sides. Thickness tolerances is within +/-.005" from nominal on 1/4"- 4".

Flatness tolerance is maintained within .015" on 1/4"-5/8" thickness and .005" on 3/4"- 4" thickness. Thermal Cycling can be performed up to 800° F under controlled conditions.

MIC 6® Aluminum Cast Plate is produced by continuous casting with each thickness individually cast. By utilizing the most recent developments in casting techniques, the molten metal is continuously fed, eliminating defects from lapses and seams. Thermal gradients are stabilized since heat is removed from both plate surfaces at a balanced rate. The employment of a SNIF filtering and degassing system ensures an end product free of voids and impurities.

[RicknBeachcrest]

I just received an order from Midwest
https://www.midweststeelsupply.com/s...FQFubAodLy3rZw

This is nice and flat aluminum and really nice to machine. They will also cut it to the size that you need. I've order from them twice and both times the order was shipped out the next day.

[dmiller47591]

You haven't specified what parts of the machine you want to make out of aluminum. But I do want to put my 2 cents in before you start thinking you need to machine all the stock used to build your router. I suppose you are talking about "main member parts" here i.e. gantry beam, gantry sides/uprights, z to y attachments, and so on. For those I would worry more about the material withstanding the forces that will act upon it. Weight load and cutting forces on the gantry beam, torsional forces on the gantry sides, all that. Using Young's Modulus of Elasticity Young's modulus - Wikipedia, the free encyclopedia, and the calculations here Second moment of area - Wikipedia, the free encyclopedia.

Now I'm not saying you should by any old piece of twisted bumpy, humpy sticks of metal. But the linear rails you are using are straight, right? You may need shim stock to keep them parallel or on the same plane, however you build. Take a look at carveone's steel channel rebuild log. He used steel channel. Have you worked with that stuff? Not flat, not straight, it's hot rolled, so it's pliable all the way down the rollers at the steel mill, and then it cools and warps some more. He used ahren's carriages (CNCRouterParts) with a long piece of cold roll (.250") for them to ride on. I haven't read the whole log (it's got more pages than the Bible) but I'd BET he used some shim in that one.

Linear rails define the majority of straightness for machine travel. Sometimes shims help to flatten the surface the rails mount to. Theres also precision leveling epoxy (Surface Plate). You "could" pour a precision surface plate in the trunk of a totaled out Grand Am. The base would be screwed, but the plate would be flat_________________________________________

Don't get too hung up on it, let us know what your build ideas are. There's lots of help on here.

[CarveOne]

I started building my 3rd machine with C channel. There were a number of reasons that I rebuilt the frame using 3/16" x 1-1/2" x 3" steel box tubing and I'm happy that I did. The C channel had a 3/32" bow at mid span of the 48" side tubes. I attribute that to a slight bow in the metal and it got even worse with my welding. The corner miter weld's rigidity was just not acceptable either. There are better ways to do the corner joints, but I didn't plan well enough. Aluminum roof flashing makes good shim stock that can be cut to shape with household scissors. It's about 0.008" thick. Stack layers as needed.

What I have now is much better even though the box tubes are not machined flat, the amount of shim stock between the rails and the side tubes is minimal, and the carriages are tracking really well.

Start reading at the most recent pages. It only gets worse as you go back through the thread toward the beginning.

CarveOne