question about used Omniturn GT-75s

If I'm looking at used GT-75s, what do I need to check to see if the machine can support C-axis milling, or what all do I need to upgrade a machine without it? I want to make, among other things, this part from 485 brass round bar:


To gauge size, that's a 10-32 thread.

To head off the obvious alternate answer, no the material is not available in hex stock. Besides, I need mill-turn for other jobs beyond just this part.

modlbtr said:

If I'm looking at used GT-75s, what do I need to check to see if the machine can support C-axis milling, or what all do I need to upgrade a machine without it? I want to make, among other things, this part from 485 brass round bar:
View attachment 309103

To gauge size, that's a 10-32 thread.

To head off the obvious alternate answer, no the material is not available in hex stock. Besides, I need mill-turn for other jobs beyond just this part.

Click to expand...

yes if you get the c axis option.
bewarned tooling for live milling is kinda weak, you wont be doing alot of hogging/heavy cuts. but the parts come out just fine. also you will loose some tool count with live tools.
if you can think outside the box you wont loose much room ie making your own tool holders.
you may or may not be able to do that in one operation but I doubt it due to tooling. if your relying on cadcam software to do the programming better learn g-code 1st.

It very well may be justified, but I would certainly verify that no one already carries a part that will work in the application:

McMaster-Carr
MH – Beswick Engineering

Most of the suppliers of these will provide custom variants at very reasonable prices. Part like this are running $1.50 each at stock retail, maybe $5 low volume custom.

I thought I would provide some input on the on the small gang lathe in addition questioning the part shown.

The top performing machine in this category would a Hardinge GT-27SP. These can be had for $7500-$12,000 with a fanuc 18-T. I don't think these got rigid tapping until a 21i-T, but maybe a 18i-T had it. C axis was an option. They have a big footprint for their capacity, but are known for being extremely accurate.

Others to look out for are the Fagor based variants that are all the same machine by Dynamic, CMS, CNCnew GT27 or GTS27. There is a slant bed version, but I am forgetting it right now. Stay away from dealing with Dynamic due to fraud practices. CNCnew seems to be regarded as the best current servicer of this group of machines.

For production work in this size, an SNK Prodigy GT-27 makes a lot of sense: SNK Prodigy GT-27 GANGTOOL LATHE | eBay

Shouldn't have any problem making your part on the gt75. If the gt75 your looking at has the older G2 or G3 computer control on it you will need to upgrade to the G4 computer, cost is around $4,000 bucks. Then the c-axis kit-control, new motor, etc will run about the same, $4000 so you are looking at $8000 total but you will essentially have a new machine. I just did this exact thing to my gt75 and it works like a charm. Omniturns are great machines both the GT75 and the kits on Hardinge lathes. And you will never find a better group of people to help you with any problems then the crew at Omniturn. If you find a machine your interested in buying get the serial number off the back of the control and call them, 541-332-7004. They can tell you the history of the machine and what you need to do to upgrade.

If you find an Omni-Turn for sale, check the serial number on the control. It will read something like xxxxG35MB ( of B could be "Y") where "xxxx" is a series of numbers. The G35 indicates a "G3" control if it is G4 in the serial number, it is the latest "G4" control. The "B" indicates Baumuller Drive, "Y" indicates Yaskawa Drive. Both B and Y indicate it is a "C-Axis" machine. Without the B or Y it is a 5hp machine (no C-axis).

What Newtonsapple said about the Hardinge GT27 is pretty good, but you do not need the C-axis. Mine has indexing and we made similar parts in stainless. Milling with indexing may be a little slower than turning a hex with C-axis. Never had a C-axis machine to compare.

We run have run conversion Omniturns for many years and recommend them for low cost to operate and very good support. A friend just bought a used/broken Omniturn GT27 and remarked how helpful the Omniturn people were on getting it running.