What side loads should wedesign to?

[pvogtcharlotte]

Folks,
I am designing a Z axis to add to an X-Y table. This is a DIY
CNC project. The X & Y are very stout.
If I would like to use the machine to mill aluminum parts,
what side load should I design to?
Thanks for any help,
Paul Vogt
Charlotte, NC

[NC Cams]

How fast do you want to cut?

How heavy are your tables?

How thick is the aluminum?

How sharp are your cutters?

How much spindle HP do you have?

How deep of a cut do you want to make at one time?

HOw much "drag" is coming from table? IE is it gib mounted or on linear/box'd ways???

These are but a few of the quesions that need to be answered in order to figure out/properly engineer the answer to your question.

Since, effectively F=MA +CF,

your F is purely dependant upon the mass of the stuff moving/to be moved, the acceleration and your cutter force.

[pvogtcharlotte]

dear NC Cams,
Thanks for the reply. I suppose I would like to be able to make about
a 1/4 in deep cut with a 1/2 inch endmill. (ploughing staight thru).
I don't know speeds and feeds, but I'm hoping this might be possible
with my Bosch woodworking router. Maybe you can just tell me if
I'm dreaming or not.
Thanks,
Paul

[ViperTX]

Bosch router 1/4 inch deep with a 1/2 inch mill.....be prepared to go real slow...like a feed rate of 0.005 per sec. (or less) in aluminum.....boy the bearings in the Bosch....are not going to last a long time....

[NC Cams]

Before you get carried away even speculating that a Bosch router would cut aluminum at the speeds and feeds you desire, I'd respectfully suggest that you do some investigation into appropriate cutter speeds and feeds that might even fit the router.

The Machinists Handbook gives some basic data for speeds and feeds for cutting materials. For example, in cutting steel, if you cut with HSS try 88-95 SFM is reasonable at 5-10 in/min at heavy cuts in mild steel), if you are using carbide, you use another. Hot rolled is at a different speed/feed than 4140PHT. ALuminum alloys too have optimum speeds and feeds. ANyway, there is an optimum cutter speed and feed for any material.

Once you learn/discover what the realites of cutter capabilities are, you then start to look at your proposed cutting spindle speed windows and HP of your proposed "mill". Do they fit within each other's operating windows (on a load per tooth basis)??? In this case, probably not.

Routers are typically designed to cut materials NOT as robust/dense as steel or aluminum (IE: wood, plastic, foam etc). Speeds and feeds coincide accordingly and that's what routers are designed and meant to be used for....

Ok so you have a router want to mill metal, if you do the math (cutter speed in RPM vs cutter OD) it should become self evident that the probability of "plowing" a 1/2" mill 1/4" deep (without coolant - recall that you're dealing with an electric router) borders on at best should be considered wishful thinking.

Bridgeport mills suck when you try to mill hardwood molding (no matter how hard I tried and I did try). I wouldn't even think about trying to cut 1/4" steel or aluminum with my Craftsman router.

[pvogtcharlotte]

Wow!
Thanks for taking the time to give me this information.
I'll take advantage of your suggestions and try to
learn more about this.
I'm

[WhiteTiger]

Originally Posted by NC Cams Bridgeport mills suck when you try to mill hardwood molding (no matter how hard I tried and I did try).

Did you try using a speeder? It's not that tough to get tool speeds into router range (30-40k rpm). I knew more than one guy in the seattle area using boeing surplus mills for intricate woodworking.



Tiger

[pvogtcharlotte]

Wow,
I really appreciate you taking the time to put this information
together for me. I'll spend some time looking for a machinists
handbook and get educated. It's so nice to get pointed in
the right direction.
Given all of this, I still am facing a decision about the design for my
z axis. I will either use thomson rods, or some kind of linear slide.
Do you have any opinion about which might be better? One thought
is that I can't predict the direction of the load since I may be cutting
in any direction. Maybe thomson rods with bearings would be better
for this reason. Any thoughts?
Thanks again for your earlier response.
Best Regards,
Paul Vogt
Charlotte, NC

[ger21]

Originally Posted by NC Cams Before you get carried away even speculating that a Bosch router would cut aluminum at the speeds and feeds you desire, I'd respectfully suggest that you do some investigation into appropriate cutter speeds and feeds that might even fit the router.

Onsrud makes quite a few types of router bits for cutting aluminum, with recommended feed speeds of 100-150ipm @18K rpm, for 1/4" diameter tools with 1/4" depth of cut. www.onsrud.com

As was mentioned, whether your Bosch is capable of that is a different story.

[pvogtcharlotte]

Gerry,
Thank you for the good information.
I looked at the web site, and will spend more
time there getting an education.
Best Regards,
Paul

[ViperTX]

Linear rails are your best bet.