Should I use MIC 6 Aluminum or Regular Plate Aluminum

[newpatch]

HI All,

I want to use 3/4" aluminum for my gantry uprights but I'm not sure which to get. Is MIC 6 worth getting over regular plate aluminum? It's more expensive and I'm not sure if I budget can handle it, but I might have to bite the bullet. Aluminum extrusion would be another option but I'm shooting for a more narrower type of gantry. Something like this but with low profile bearings:



My gantry uprights should be 10-12" wide and 16-17" tall.

newpatch

[Geof]

The advantages of MIC 6 over regular 6061 plate are that it is flatter, has a closer thickness tolerance and is stable which means when it is machined it will not warp due to the relief of internal stresses. A disadvantage is that threads in MIC 6 are not as strong as those in 6061 particularly fine threads and installing and removing bolts on a frequent basis can lead to early thread failure.

I think none of the advantages are applicable to your planned use but the disadvantage could be important.

[DonFrambach]

One way to get around the problem of weak threads in Mic-6 aluminum (or aluminum altogether) is to use steel weld nuts. I got mine from McMaster-Carr. Here's a photo from my build thread where I used several in a Mic-6 aluminum plate:

[crane550]

Newpatch,

I think simple old 6061 will suits your needs nicely. I have used both, and each time I used MIC6 I thought it probably was not worth the cost. Certain applications call for it, but quite frankly your build methods (like mine) will probably have more variance then the metal will. It's like measuring with a micrometer and cutting with a chainsaw, if you get the idea.

Good question, and keep up the progress!

[newpatch]

Another thought I had was to buy the plate aluminum and have it milled flat, but I think that would cost more.

Would using aluminum extrusion be acceptable? I'm planning on using it for wooden guitar bodies, necks, and aluminum brackets....and hobby stuff.

newpatch

[Drools]

hi newpatch, I used plate but had it milled flat (one side only). The coat was about 50.00 for the gantry uprights. The Z-axis adaptor plate needed both sides milled flat that was about 25.00 (8"x6" plate).

[newpatch]

Thanks dools,

I would have thought both sides of the gantry need to be milled?

Also, what place did you have it milled? I was planning on getting the aluminum on flee-bay...maybe the seller has a mill.....

[Drools]

well the side which have the blocks mounted was milled flat, I left the other side alone. I called around locally for milling rates and several small shops were glad to do the work once I told them what it was for. Maybe the cost would have been more if I just dropped the stuff off with a work description, but I talked to the shop guys and we hit it off so to speak.

[newpatch]

Thanks drools....I'll check around locally first.

[louieatienza]

newpatch, the way to work around mic-6 is to use its flatness to your advantage. As in the K2 picture there is no advantage to using milled flat stock for the uprights because the accuracy of the gantry beam doesn't solely rely on the flatness of the uprights; it's more the mounting holes that will determine the accuracy, and they can be slotted to adjust for any inaccuracies.

The mic-6 would definitely be beneficial in the carriage, where as shown the linear blocks bolt directly as well as the rails, so you only need to worry about alignment along the surface, since you know the thickness is consistant.

I do find it machines easier than regular 6061, but maybe not as well as 7050 or 7075. On my current build, I tried to arrange the mic-7 plate in such a way that I can take advavntage of its flatness, which removes one variable when setting up and machining. Meaning: I rely on the surface of the mic-6, and not as much on my cut edges which myght not be to the same tolerance.

[newpatch]

I see what your saying louieatienza,

According to the K2 site all the machines use 6061 aluminum...It might be milled flat but it doesn't say...

How much of a tolerance are we talking about when using mic 6 over plate aluminum?

newpatch

[louieatienza]

I see what your saying louieatienza,

According to the K2 site all the machines use 6061 aluminum...It might be milled flat but it doesn't say...

How much of a tolerance are we talking about when using mic 6 over plate aluminum?

newpatch

I had a piece of 2 foot square aluminum plate, 6061 that had a "warp" of about .01-.02". Compare this to mic-6 at the same size is ground to about .002-004"

Now, this may not seem like a lot, but if you are using profile rail, a couple hundredths can lead to a tight spot or binding.