Feed Rate?

[bearwen]

Hello all,
Well I have been playing with meshcam and I love it however I am wanting to do relief carvings and etches but reliefs mostly. I have designed some reliefs that are not to detailed if you are familiar with the gibson tutorial from the yahoo forum then the detail is a little more than that. However I am doing reliefs that are roughly .75" to 2" tall and the overall size ranges but for now lets say it is 24" tall and 36" wide well I am wondering on a home made mill (similar to jgro but 5' x 5' x 8" cutting surface and it is made out of metal not wood) with a 3hp router 1/2 10 screws and 260 oz motors what is a realistic feedrate? I have been exporting to cutviewer and for the above size with a 1.25" z relief it is coming out to like 7000 min ( 116 hours) to cut this just seems way off. What size bits and stepover and feedrate etc would be ideal for something like this I just dont know how to set it up and what my machine can do as I am not finished building it yet any ideas as to what I should do?

Thank you all

Berry

[robgrz]

The feedrate parameters and overall machining time will be defined by the following:

1) Overall size
2) Relief height
3) Stepover
4) Tool diameter
5) Relief complexity
6) Stock Material

If you're machining out of wood then it may be a valid tradeoff to reduce the machining time with a larger stepover but spend a little time with some sandpaper to clean it up. I know that this has become my preferred way to work on a Sherline where the machine can hiccup after a very long machining time.

If you can fill in the other parameters then I'm sure others can suggest some starting points for you.

-Robert

[ger21]

With 1/2-10 acme and 260 oz-in motors, I'd guess somewhere around 50 inches per minute. A 3HP router like a PC 7518 should be able to handle speeds close to 150-200ipm, depending on tool type and depth of cut. Unfortunately, speed cost money. Lots of it. But, like Robert says, you can use larger tools, with larger stepover values to cut things quicker, but it depends on the detail of the relief.

You asked what would be an ideal speed to cut a 24x36 inch relief. As fast as possible. Probably in the 400 inch/minute range. But that would probably triple(if not more) the cost of your machine. The ideal stepover and bits depends on the detail needed. Use the largest bits with the largest stepover which will give you the desired results. That will get the job done as fast as possible. But a 24x36 carving will always take a long time, even with a fast machine.

[bearwen]

Thanks for the replies I guess I will just have to play some more darn the luck ha ha.
I think maybe I will change screws to a 1" - 5 turn? so 125inm would be 625 rpm that might be doable maybe spin the nut not the rod since rod is 1" diameter well see upgrades are always expected.

Berry