[etard]

Hey guys been lurking and learning here for a few months. I am going through the CNC certification course at the local college and am really enjoying the capabilities CNC offers over crankin' handles. I thought I was a manual kinda guy, but once I started learning to program, the ceiling of capabilities has been lifted and now I am looking into blue sky if you gather what I am saying. Anyway, I have collected a decent shop full of manual machines, 2 South Bend 10K's, a Diamond hrizontal mill, a Rusnok benchtop mill, and a Clausing 8520. The 8520 is considered to be the best mill in it's size and very comparable in my mind to the IH clones as far as size and capability. It is a knee mill and this offers some unique challenges as far as CNC conversion of Z axis, but I believe this can be worked out with some extra effort.

So here is my question to you guys, Considering I already have the mill on hand, I could begin the conversion today. If I could get the ways reground and scraped with a total investment equaling that of the PM-45, which mill would be better and sturdier?

Here are some pics of a Clausing 8520 for those not familiar:

Attachment 181622Attachment 181623

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Having converted a 9x49 knee mill, and a bed mill, I would opt for the bed mill every time, unless you needed to longer travels of the knee mill (which sounds like a non-issue in this case). If you use tool-length compensation, a knee mill is inconvenient, especially with Mach3. On a knee mill, you really want to use the knee for tool length compensation, but Mach3 does not directly support this. I did it on mine, using custom macros to take the place of G43 and G49, but it's not an ideal solution. Plus, as you noted, a quill drive can be tricky to do well. I designed one that works well, but it certainly presented some design challenges to make it as precise as I wanted. Also, the knee will in inherently add a small amount of slop to the whole system. Finally, if you plan to use flood coolant, a knee mill is an absolute nightmare to enclose. In fact, that was one of my main motivations in switching to a bed mill - it is trivial to fully enclose, even with something as simple as shower curtains. The knee mill required an enclosure around the table, a huge chip/coolant tray under the entire machine, plus shower curtains to get the many remaining "holes".

Regards,
Ray L.

[TiagoSantos]

I love those little Clausing mills, I'd love to have one to stand next to my Clausing 111 mk3 lathe

I think I'd keep it manual though and convert something else.. But maybe I'm just being sentimental.

[jid2]

We have a clausing at work and my PM45 is much beefier in all respects.

[etard]

Ray,
Thanks for that insight, I will have to look up some of those problems you are encountering with the tool-length compensation. That full on CNC offered by Precision Matthews is looking like a good deal to save up for.

I think Jid2 nailed it down for me, I did not know the PM-45 was beefier, I guess I will be selling some things on Craigslist and ebay and saving my coins.

Thanks for all the help guys.