I am looking online at different 5 axis cnc routers. After seeing the prices for a few used ones by Thermwood ( $65,000) I am considering a 3 axis machine. ( around $8,000)
I am wondering can a 3 axis machine get a class a finish, not leaving machine cutter ridges in the part?
Also can rigid urethane foam be primered straight on top of or does it need to be sealed with something prior to plug primer?
Any machine can get an A finish, it comes down to the step size and cutter size. The smaller both are the finer the cuts but the longer it takes to machine, so it will be a trade off between finish and speed.
I’ve sprayed Duratec directly on foam but it is quite thirsty and kept needing more coats, thus I used a lot more and it took more time.
I can get class A finishes off my 600 dollar cnc mill/router but like Moke said finishing passes add time. I ran a cycle once with just roughing and it took 5 minutes, added finishing and it went up to 13 from the CAM estimate.
13 minutes ain’t bad at all. I wanted to be able to make foam plugs that are as large as 6ft x 2ft x 1ft.
What CAD/CAM software do you guys use? I looked on MasterCam’s site and they have like 5 or 6 different software programs. I have a feeling the software is going to run 5x the cost of the machine!
edit: oops got carried away… i guess a full version of a cad cam software can run $5000 or so. makes me wanna go the dark alley route
I use a heavily modified Sherline 5400 CNC. Mostly its just the spindle and control hardware at this point. You can get a sherline 4 axis turnkey set up for 3-4k depending on the options and it will handle the majority of projects. I upgraded mine for more milling area and for ease of tooling. I am able to get mirror finishes on everything it just depends on the feed rate and if I use coolant.
I use Solidworks to build my parts and Meshcam as my cam software. I also use CAMBAM when its a simple shape or for engraving. They are both cheap and very powerful if used for their strengths. Meshcam is great because its so stream lined and straight forward. I use it for 4th axis work and when I want one file for more involved two sided machining. CAMBAM can be as useful as Meshcam but its not as finished for UI and still has some rare hiccups in long milling routines. If you check the gcode beforehand you will be fine but its still a very very good beta.
13 minutes was for a tiny part. The entire Ncode file was some 40 odd lines. From what I’ve read on CNC forums it’s not uncommon to leave machines on for days if milling complicated parts. It depends on how you set up the code.
Why don’t you make one by your self one? The money that request for CNC machines are too high, you can make one CNC to create one strong CNC!!!
Get login to www.cnczone.com and take some ideas, I do the same. I have already buy the CNC Router :http://www.kress-elektrik.com/Power-tools.71+M5eb130ce52a.0.html?&tx_commerce_pi1[catUid]=17&tx_commerce_pi1[showUid]=1035
and now I am in search of Step motors.
The cost for rooter is 130euros (180-200$) and the step motors over 700-1000euros (1500$) 4 axis + PC controller.
Check it and you will see.
Chances are you will not be making many plugs with a perfectly smooth surface from the machine. While I’ll admit is is possible, in most applications of any real size (such as the 5x10ft+ envelope you are looking at with the thermwoods) it is more time efficient to machine it to a very reasonable surface finish and then sand it to your finished surface.
I’m with George on this one, you should build your own. I bought a vertical mill first and used that to build my gantry mill. The first mill had a cut envelope of 36"x24"x18" and the new one can do 6’x6’x4’ with 4 axis. Wish I could find a controller for a 5th axis to add that on. But no luck yet… Funny thing is, it was about 3 grand less to build the gantry then buy my vertical mill. That’s why I say build one. THK is a good source to get your Linear rails and feed screws. http://www.thk.com/us/
One thing you will want to look for is a fast feed rate. Something with at least 100IPM if you want to machine stuff this big. Here is a 72" R/C boat hull I am going to be machining this weekend. At 20IPM it would take 15 hours just for the finish pass, if I change the speed to 100IPM the time est. drops to 3 hours. :eek: So keep an eye on that feed rate.