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Author Topic: General question about small CNC mills  (Read 1856 times)

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Re: General question about small CNC mills
« Reply #10 on: November 09, 2017, 07:46:28 PM »
Billy,
You actually will learn hand coding faster by using a Cam program because you get to see code generated essentially by an expert for your part. I generate all my code with Cam and I start every new program in single block mode, reading each line before executing it until I am confident it is where it should be and won’t crash.  The nice part is when it needs a small adjustment that happens quickly in Cam and I keep moving forward.
Re: General question about small CNC mills
« Reply #11 on: November 09, 2017, 07:47:58 PM »
Do not download demo version of CamBam. Get full version which is free for 40 sessions
Re: General question about small CNC mills
« Reply #12 on: November 09, 2017, 11:16:54 PM »
Hi Guys,

OK, I understand about breaking the tool. I also downloaded CamBam and messed with it a bit.

 I  got the part programmed correctly and cut the part in steel without issue. So far so good. There was a lot of fooling around with the math to get the cutter offset correct. I am a old guy and now have to work harder to deal with math in general. I advise never getting old...lol

 I am looking forward to the time when I can use the tool radius offsets. I'll get there. The CNC Programming Handbook arrived today and I looked at it a bit. It seems to be pretty well written and understandable. Many of the issues I am faced with have less to do with CNC than just machining in general.

Another option I considered today was to power coat the part and just make it out of steel. I actually may try that as a test in any event. The part is not subject to very much abrasion just the effect of fertilizer for the most part and some type of coating may work well enough.

At least I got the part cut out of steel and that is pretty good progress for me. It is for sure not a complex part but for my first attempt at hand writing code it was a bit of a challenge. 

Anyway, thanks for all the help and feedback.

Billy
« Last Edit: November 09, 2017, 11:31:32 PM by Planobilly »
Re: General question about small CNC mills
« Reply #13 on: November 10, 2017, 10:14:52 AM »
Billy,
When I was programming by hand I used the G40 offsets all the time. Few low cost cam programs do G40 offsets and you find that you don’t really use them once you use a Cam program.

A little secret if you want to try them. Add a short approach move in X and Y to the start of cut location. Before lowering the Z call G41 or G42 then move to the start point. You will see the tool move off to one side by the radius value then move to the start point. Now you can lower the tool in Z without gouging the part.  When the cut is finished raise the Z before issuing G40 to cancel the offset.
Re: General question about small CNC mills
« Reply #14 on: November 10, 2017, 03:50:45 PM »
Thanks Gary,

I think I will program a square for example and use the G40 offset. I will cut something easy to cut so I am only dealing with learning the programming issues.

I cut two more of the "T" parts and damaged the cutter. Broke one of the four teeth. Not sure just what happened but assume it was caused by a chip. This little machine is not very ridged so that could have been the cause also. I assume breaking tools is something that will happen from time to time. The cutter I broke was HSS. I replaced it with a carbide cutter to finish up the cut without further issue.

This little machine is kinda like my pickup, it will pull a 18000 lb trailer but it don't like it...lol  Just because some machine can be pushed to do something does not make it a good idea.

Thanks,

Billy
Re: General question about small CNC mills
« Reply #15 on: November 14, 2017, 01:25:40 PM »
^ There's your problem, it's a little outside its comfort zone.

To be honest when I saw the drawing I thought it was an excellent part for a profile cutter. I get quite complex parts WJ or laser cut all the time and just do finish machining for bearing fits and precision locations. It's so much easier. I'd go for laser cut A2 stainless and practice on the mill with some nice 6082 aluminium, it's so much more satisfying and your tools will last way longer. Happy learning ;)
Re: General question about small CNC mills
« Reply #16 on: November 15, 2017, 11:12:47 AM »
Both the machine and I are "outside our comfort zone"...lol Big learning curve for me.

Here is a photo of the machine. I got a 3/8 aluminum plate that I will make into a table for the machine. I will mill slots for the hold down and drill and tap holes also. At the moment I  made a little spring loaded pencil to draw out the limits of the machine. I am having a bit of trouble trying to figure out how to set up the home position. I do not have a home switch made yet. I will ask some questions when I study the Mach 3 instructions some more.




Thanks,

Billy


 
« Last Edit: November 15, 2017, 11:26:01 AM by Planobilly »
Re: General question about small CNC mills
« Reply #17 on: November 15, 2017, 11:22:26 AM »
Well, one possibility in the absence of a home switch is to bolt a block on one corner of the table and square it up with the cutter, then to get your "home" positions in X and Y just touch off it with a wiggler and set the zeroes by hand.
It's a nice little mill though, you should be able to make some tidy work with that.
Re: General question about small CNC mills
« Reply #18 on: November 15, 2017, 11:28:31 AM »
Thanks,

I have to run take my wife to Miami. See you guys in a bit.

Billy