[Allfather]

I've been building custom higher end astronomy (telescope) equipment. I have found I have two basic needs. Cutting out aluminum plate into rings up to 36" width. These rings are generally 1/8" to 1/2" 6061 aluminum plate. I then need to machine all sorts of connecting components from solid aluminum but these are smaller pieces generally where 6 x 6 x 12 would probably work. I've pretty much resigned myself to needing two machines with the smaller parts needing a more capable milling machine.

I've just been having machine shops water jet cut the aluminum plate and mill the smaller parts. I would like to see if I could build or buy a gantry router that would work for the aluminum plate material.

I don't want to use a DeWalt router but would rather go straight to a good spindle and motor.

I'm very mechanically inclined as I grew up on a ranch where TIG welders, bailing wire and duct tape are necessities of life. I've been eyeing these machines for awhile and it looks like they are becoming more mature.

I've learned not to go the cheap way so I would budget around $2,500 for these parts rather than the $1,000 kits.

This is my first post by the way so I'm not super familiar with this forum yet.

Greg

[wizard]

Here is my opinion, hopefully others will chime in soon.

I've been building custom higher end astronomy (telescope) equipment. I have found I have two basic needs. Cutting out aluminum plate into rings up to 36" width. These rings are generally 1/8" to 1/2" 6061 aluminum plate. I then need to machine all sorts of connecting components from solid aluminum but these are smaller pieces generally where 6 x 6 x 12 would probably work. I've pretty much resigned myself to needing two machines with the smaller parts needing a more capable milling machine.

I've just been having machine shops water jet cut the aluminum plate and mill the smaller parts. I would like to see if I could build or buy a gantry router that would work for the aluminum plate material.

If you are having parts water jet cut I would consider doing so in the future. Milling is less than ideal for what you are trying to do with these large sheets. If you are getting good enough tolerance and surface finishes I don't really see a big advantage to trying to mill such large rings.

The obvious exception here is that if you want to mill specific features into the rings. Gear teeth, engraved lines, engraved text or other machining that can't be done well on a water jet.

I don't want to use a DeWalt router but would rather go straight to a good spindle and motor.

I'm very mechanically inclined as I grew up on a ranch where TIG welders, bailing wire and duct tape are necessities of life. I've been eyeing these machines for awhile and it looks like they are becoming more mature.

The problem with machine building is that you often need a machine to build the machines! If you have access to a general purpose machine shop a relatively small but robust machine can be done fairly easily. A larger machine can be a huge problem. My thinking here is that you are going to want tolerances and surface finishes more like a mill than a router.

In reality what you are building is a gantry mill.

I've learned not to go the cheap way so I would budget around $2,500 for these parts rather than the $1,000 kits.

The thing with a budget is that you really can't set a price until you know what your expectations are. Knowing a bit about astronomy equipment I can imagine that some of those parts might be of high tolerance.

Several years ago I had a good but short conversation with a guy that was building telescope focusers and other parts for scopes. He started out with a Chinese mill with a self made conversion to CNC. After the business became a success he went out and purchased a couple of Hass machining centers. What is important here is that he wasn't shy at all about declaring the Hass machines the best thing he ever did for his business.

I'm not trying to discourage you but a $2500 budget for a machine primarily focused on machining aluminum isn't much be it a router or a mill conversion. Of course the cost is very much a factor of your DIY abilities and and local costs for machine shop services if you need to use them. Stiffness of the design is a factor but your also really need a lubricant/coolant solution if this is the primary focus of the machine. In an ideal world that would mean an enclosed machine to contain the coolant mess.

There is a good possibility that going with a CNC mill first might enable you to build a router cheaper but I'm not sure if you have much of a need for a router if you continue to have parts cut out at a water jet service. The reason I'm wondering about the router is that machining sheet metals with end mills isn't always the best way to fabricate a feature. At 1/8" you would still be dealing with these machining problems, 1/2" may be less of an issue.

This is my first post by the way so I'm not super familiar with this forum yet.

Greg

Welcome aboard.

Hopefully lots of people will see this thread. I'm of the opinion that you need think a bit about how to best go about moving your business forward. I'm not sure I'd consider a router first. If this isn't a business then it really doesn't matter which way you go. With your rings hitting 36" in diameter it is completely possible that your could build a moving table design and get really good performance similar to a mill. This won't be a cheap machine though. Also a moving table this size becomes a bit of a space issue.

The reason I'm talking about a moving table design is that you should be able to build a rather stiff machine. One that can hold tolerances and with enough effort remain orthogonal in operation. Such a machine might be able to handle all of your aluminum needs. Done well though might require adding another zero on your costs / budget.

[ger21]

Are you looking to design and build your own machine, or buy a kit or working machine?

If the former, then your budget is probably at least $1000 light for a decent machine to do what you want, if you have the tools and equipment needed to do it.
If the latter, you need to triple your budget.

Either way, what you end up with won't be ideal for cutting large sheets of 1/2" aluminum.

[pippin88]

If you want true round rings you might be best off with a rotating workpiece and stationary tool. A vertical lathe of sorts, or a rotary axis mounted vertically may be best.

[Allfather]

Thanks guys. I knew this was a tall order plus the rings are kind of oversized and are better off at a machine shop. I'll turn my attention to a CNC Mill for all the little parts. Budget will go up 4x for that machine. I guess I'll post over in the CNC Mill Metal area.

[wizard]

Thanks guys. I knew this was a tall order plus the rings are kind of oversized and are better off at a machine shop. I'll turn my attention to a CNC Mill for all the little parts. Budget will go up 4x for that machine. I guess I'll post over in the CNC Mill Metal area.

We will hate seeing you go, especially as you just got here. You are likely making the right decision here, at least it looks that way from afar. You may want to cinder commercial milling machines in this size category. It is fairly surprising how cheap Chinese sourced machines can be. If you expect to stick with aluminum look for a machine with a relatively fast spindle.

[msimpson99]

I have milled some rather large 1/2 aluminum plate with the KRMx02 CNC. There are many considerations though. While a machine can be built that has the rigidity to cut a piece of aluminum plate that thick and at the size you want ( I have done it on the KRMx02) there are other considerations.

Clamping
You must have the ability to firmly clamp the plate to the table. This can mean more than just attaching it at the edges.

Chip removal
This is very critical. You will certainly need some addons to accomplish this. Compressed Air/ High static pressure vacuum system. You will also need some sort of lubrication. For aluminum a good misting system can do wonders. It will not be a fast process.

Time
Look for this job taking between 1-2 hours depending on settings and finish required on a CNC router with a bit designed for cutting aluminum on a CNC router.

Cost
The KRMx02 build size that would accomplish this would cost you at least $5000.

[Allfather]

Thanks for chiming in. I'm not gone yet!

I see that I need an actual milling machine that I can use to machine small aluminum parts first. Those Tormach's look like they would work. I'll have to re-budget for $8,000 - $10,000 for such a machine.

I'm very mechanical and can build just about anything and have a full shop of woodworking tools. However, I would like to get more into machining.

I'm very interested in the router tables for cutting plywood for wood projects.

Maybe I should change my question to a good cnc router that can cut baltic birch plywood up to 3/4". I would want it to cut very precise otherwise I would just use a scroll saw.

[wizard]

Thanks for chiming in. I'm not gone yet!

I see that I need an actual milling machine that I can use to machine small aluminum parts first. Those Tormach's look like they would work. I'll have to re-budget for $8,000 - $10,000 for such a machine.

Tormachs have a good reputation and if you choose a machine with a high speed spindle should be able to handle aluminum fairly well. There are other low cost CNC machines on the market though so do consider them all. Also once you get into the $8000 range it really pays to start looking at used machines, especially if you want to handle large sheets.

I'm very mechanical and can build just about anything and have a full shop of woodworking tools. However, I would like to get more into machining.

I'm in a similar situation though maybe a bit more wood focused.

I'm very interested in the router tables for cutting plywood for wood projects.

A router table can be good for aluminum but you really need to consider robustness beyond what is seen in wood focused machines. Especially if you expect to do commercial work. Right at the moment though it sounds like you are on the right track looking at a conventional mill.

Maybe I should change my question to a good cnc router that can cut baltic birch plywood up to 3/4". I would want it to cut very precise otherwise I would just use a scroll saw.

You see this I don't understand as I can't imagine a scroll saw being that precise.

In any event you need to get a handle on what you would want from the machine. Half sheet capability? Vacuum hold down? In any event you can build a wide array of machines suitable for 2/4" plywood. The lowest end machine will barely leave you with acceptable results. A high end machine can cut very well but set the pocket book back a bit.

In any event do read the stickies. There is very good information contained in them.