Help with .063 Aluminum Routing

[MarkEMark2]

Hi All:

I am planning some aluminum tests with a SB desktop D2418. Aluminum is a standard grade (nothing hard or fancy. It's used to make electronic's housings) and is .063 thick.

I am wondering if you guys could offer me some starting bit types and cutting and spindle speeds for this material? Any reference would be a great starting point for me as it will all be trial and error and I am not sure an adequate place to start.

Also wondering what you are using for a spoil board and clamping solution fior this kind of material....

Thanks!

Mark

[Brady Watson]

Mark,
This question has been answered many times if you do a Forum Search - but generally speaking, 13-15,000 RPM, 0.7, 0.5 MS should get you in the ballpark.

There are a few rules when cutting AL. ALWAYS ramp into the cut & never drill or plunge straight down into the material. AL will weld itself to the tip of the bit, rendering it useless. If you do need to do 'drilling' select a smaller diameter bit than the hole to be drilled & do an inside profile toolpath - preferably with a spiral ramp plunge. You will find ramp entry options in the profile and pocketing toolpath strategies in PWorks.

You will want a single flute spiral-O flute tool for cutting AL. Onsrud & Harvey Tool are excellent choices. If you use dust collection, no coolant or lubrication are required.

In terms of hold down, you will want to make sure the AL is held down well. If it moves around, it can break the bit in short order. The ideal setup would be vacuum. I have not yet designed one specifically for the Desktop series of tools, but it would not be too difficult. A good shopvac is all that is needed to hold down most parts, but if you have smaller parts (surface area matters!) you will want to get a vacuum pump capable of delivering higher levels of suction than a shopvac can deliver.

You can use carpet tape (Ace Hardware indoor/outdoor with fiberglass mesh works well) to hold down the AL as well, but it sometimes holds so well that you run the risk of bending the AL when you go to pull it up on the thinner gauge stuff. If you cover the back of the AL with masking tape, then use carpet tape, it will be easier to get it free. Clamps and screws are not very effective in my experience, because they tend to tweak the flatness of the sheet, making it pop up in another area. You can add tabs/bridges to the AL to aid in hold down, but it all depends on the design & if you want to trim/sand tabs after you cut the parts.

Two more things...1) Wear safety glasses - even with the machine off, sometimes static electricity is generated and when you move the material, polarity can shift where you get a -- or ++ condition & AL chips WILL shoot straight in your eyes. (This usually happens with vacuum) and 2) AL sounds 'all wrong' when you cut it. It has a resonance to it that is different from anything else you've cut. As long as you choose the correct bit, and get the RPM & MS in the ballpark & the material is held down well, you will be successful.

-B

[MarkEMark2]

Thank you Brady!

My apologies for not searching the forums first. In my impulsive mind set I didn't even think that others might have had the same question

However, your summation is perfect for what I am needing, so while I will search the forum to get more info, what you offered here was a blessing. Many thanks!

I will order the bits tomorrow, and will have a go at aluminum next week.

Regarding the vacuum table:

I have made one of these for a home made router CNC I designed and indeed it works well! I have a 3/8" thick fiberglass plenum on the bot now, and I would like to make a vacuum table for this unit. It is on my 'to do' list.

I will search the forums for any plans or advice on vacuum tables and or cut files, but do you have any words of wisdom regarding depth of the grooves and thickness of the material for the base board? I am wondering if the 3/8" fiberglass with .25 channels would be sufficient? Then a series of .25 holes drilled into the back edge of the plenum into those channels equal in area to the vacuum hose diameter/area...

Any additional advice will be sucked up like a sponge!

Mark

[MarkEMark2]

Search and you will find! Shopbot desktop vacuum table ideas...

Wow Brady: you have helped a lot of people!!

http://www.talkshopbot.com/forum/showthread.php?t=14959

[Simops]

I'm still very much an amateur and also cut aluminium parts on my Buddy for my business, mostly 2mm (5/64") and need to cut tight corners so use a 1/8" bit.
I use the solid carbide spiral O bits as well with success but recently stumbled on the solid carbide single 'spoon' flute straight bit. Have had good success with this bit at a chip load of 0.003". It also seems more robust at higher feed rates. I might be somewhat too cautious so use 4 passes. Still learning

Also as Brady says....I also spiral ramp in.....important.

Cheers

[Brady Watson]

Search and you will find! Shopbot desktop vacuum table ideas...

Wow Brady: you have helped a lot of people!!

http://www.talkshopbot.com/forum/showthread.php?t=14959

Jeez...Must be goin' senile. I totally forgot that I designed that one!

If you need additional Z room, neither layer has to be that thick. The grid can be as thin as 1/4" (but still must be ultralight to bleed properly) and the depth of the grid is fine 1/16" deep. The backer can be as thin as you want - even 1mm sintra or styrene will work just to seal it off. - Although you'll still want a decent 'mount' for your vac hose, so you might want to beef that up where the hose enters the bottom sheet.

-B

[MarkEMark2]

Brady:

After doing what I should have done before and search the archives properly, I am amazed at how prolific a help you are to the community. I assume you are like one of us: a consumer of the product and not an employee. If you aren't compensated by SB for your work here, shame on them. At least some free product for you somewhere along the line. You are a real blessing to the community, and your giving disposition is a real (very real to us SB newbies) blessing and I for one will need to learn enough to pay it forward when I am up to speed.

I tend to get so busy with my own projects that I forget to reach out and 'lurk' on boards like this to help others that are struggling.

So, today I set out to make a vacuum table that you helped us see with the old thread, and I hope my holing issues are gone!

But more importantly, thanks for showing us more than SB techniques in how to help a community.

Now, quit blushing and get back to work!

[Brady Watson]

Mark,
Thanks for the kind words. Yes, you could say I am a ShopBot enthusiast. I have owned several ShopBots and they have helped me to do a lot of things over the years. I like helping people, but mostly enjoy helping people to help themselves. Knowing I helped someone to make thier daily bread, or alleviate frustration/confusion, is reward enough for me. No, I am not an SB employee, but I do work with them as a consultant from time to time. I get to configure and work with ShopBots used in all kinds of different applications, and many times I have to pioneer solutions on the spot...which is where the whole 'BradyVac' concept arose from, among other things.

When I first got into CNC, this forum was a big help to me, since I didn't know a router from a hole in the ground. I try to keep the concept of freely giving & sharing rolling along by participating here. I hope the help I give comes back to seed the next batch of people in need.

-B

[MarkEMark2]

Good to know. You are a blessing to many.

Thanks again. I am in the process of creating a BradyVac today!

[MarkEMark2]

Mark,
This question has been answered many times if you do a Forum Search - but generally speaking, 13-15,000 RPM, 0.7, 0.5 MS should get you in the ballpark.

There are a few rules when cutting AL. ALWAYS ramp into the cut & never drill or plunge straight down into the material. AL will weld itself to the tip of the bit, rendering it useless. If you do need to do 'drilling' select a smaller diameter bit than the hole to be drilled & do an inside profile toolpath - preferably with a spiral ramp plunge. You will find ramp entry options in the profile and pocketing toolpath strategies in PWorks.

You will want a single flute spiral-O flute tool for cutting AL. Onsrud & Harvey Tool are excellent choices. If you use dust collection, no coolant or lubrication are required.

In terms of hold down, you will want to make sure the AL is held down well. If it moves around, it can break the bit in short order. The ideal setup would be vacuum. I have not yet designed one specifically for the Desktop series of tools, but it would not be too difficult. A good shopvac is all that is needed to hold down most parts, but if you have smaller parts (surface area matters!) you will want to get a vacuum pump capable of delivering higher levels of suction than a shopvac can deliver.

You can use carpet tape (Ace Hardware indoor/outdoor with fiberglass mesh works well) to hold down the AL as well, but it sometimes holds so well that you run the risk of bending the AL when you go to pull it up on the thinner gauge stuff. If you cover the back of the AL with masking tape, then use carpet tape, it will be easier to get it free. Clamps and screws are not very effective in my experience, because they tend to tweak the flatness of the sheet, making it pop up in another area. You can add tabs/bridges to the AL to aid in hold down, but it all depends on the design & if you want to trim/sand tabs after you cut the parts.

Two more things...1) Wear safety glasses - even with the machine off, sometimes static electricity is generated and when you move the material, polarity can shift where you get a -- or ++ condition & AL chips WILL shoot straight in your eyes. (This usually happens with vacuum) and 2) AL sounds 'all wrong' when you cut it. It has a resonance to it that is different from anything else you've cut. As long as you choose the correct bit, and get the RPM & MS in the ballpark & the material is held down well, you will be successful.

-B

Hey Brady:

"... but generally speaking, 13-15,000 RPM, 0.7, 0.5 MS should get you in the ballpark."

Got the 13-15,000, and I think the .7 is feedrate, but what is .5 MS?

Thank you!

Mark