CNC lathe advice

[jdholbrook]

Hello,
I've been making some parts with my little Taig CNC mill.
Some parts require a lathe and I have been sourcing them from machine shops.
In the past year I've probably spent $5K on parts from machine shops.

Not really sure what questions to ask but what I would like to do is make a CNC lathe to do the parts myself.

I need something that will allow me to use 1 1/8 stock thru the spindle and was considering converting an Enco/HF/Jet 12 to 14 x something.

I've read thru many posts on here and it looks like the Hardinge conversion would be a good route to take. Does a 5C collet system allow for bar stock to go thru the collet and closer?
Can the Hardinge use a regular chuck (I ask that with the idea of using a power chuck later)

The Auto Turret is very high on my list also.

With a budget of $5k for the lathe and drives what would you suggest?

Thanks

James

[wizard]

Ah you are at the point where it is hard to justify a CNC lathe if all you expect is to run 5K worth of parts thrugh it a year. Even a home built job.

I'd strongly suggest looking for a used machine and see if you can get one for around your price point. That is a used CNC lathe in runable condition. I'm not sure you can get to where you need to be buying and retrofitting a conventional lathe. It is not that the conversion is imposibble just that you are describing needs that can be best meet buy a machine built for what you need.

In other words coming up with a automatic collet or chuck for your bar size and a tooling turret leads me to believe that you really would be better served gettting a used machine that has the features you need.

The other thing to do with the lathe is to find other work to justify its existance. You certianly have an issue considering that that parts volumne is rather low.

Dave

[Karl_T]

5C collets, VERY common on many CNC lathes take a maximum of 1 1/16 though the spindle. If you can live with that restriction you can reduce your costs considerably. Both now and for tooling later.

I'm refitting a Hardinge CHNC with Camsoft and final total cost will be around 5K. But I'm scrounging to do it. There are many fine Hardinge lathes that can be retrofitted, a CHNC is one of the best choices because you get a turret. You'd save a lot by just going with gang style tooling though.


The Hardinge system has the collet ground into the spindle and a thread mount on the outside. In my case a 2 3/16 x 10 tpi. You can put on a chuck without removing the collet closer, handy for quick one of jobs. If you remove the collet closer/bar feeder, then you have the OD of a 5C collet (1 1/4" ?? don't have one handy right now) for through the spindle capacity.

Karl

[jdholbrook]

Failed to mention that if I had my own CNC lathe I would make even more items. I've got several designs on the board right now. One I sent to the machinist back in October and they are STILL working on and it was not a complicated part. Guess everyone is a little behind this time of year.

WHere would I look to find a used CNC machine? I've looked thru Ebay for weeks and see plenty in the $10K range. Another point is that those CNC machines weight a LOT. I can probably handle a machine that weights in around 1000 but one that weights 12000 is going to be a problem. Also space is an issue. My building is only around 1000 sq ft and pretty narrow.
I live pretty close to Houston and I would imagine that there are some used tool dealers in a city that big. I may try the yellow pages.

As of now my maximum diameter on parts has been 1", actually 24.3mm, so a 1 1/8 thru bore would be great.

Is it possible to convert a collet closer to function automatically?

What does CHNC stand for?

Thanks for the info.
James

[wizard]

Originally Posted by jdholbrook Failed to mention that if I had my own CNC lathe I would make even more items. I've got several designs on the board right now. One I sent to the machinist back in October and they are STILL working on and it was not a complicated part. Guess everyone is a little behind this time of year.

Sounds like you need a new machinest. Either that or this part is not a high priority for either one of you. From the machinest standpoint this is probably not a high value project but still that is a very long time to wait - no matter what time of the year it is.

If you have more than one potential design to run on this machine then you need to look at the requirements to do all those products. Would a 5C collet system be enough? That puts you at 1-1/16 through the spindle or there abouts.

WHere would I look to find a used CNC machine? I've looked thru Ebay for weeks and see plenty in the $10K range. Another point is that those CNC machines weight a LOT. I can probably handle a machine that weights in around 1000 but one that weights 12000 is going to be a problem. Also space is an issue. My building is only around 1000 sq ft and pretty narrow.

Auctions are one place to look. Check with local machine shops or those in near by cities that might need to clear out old equipment. There is a difference with respect to e-Bay auctions and E-Bay businesses/stores, either way be careful. Check the want adds in a major city newspaper along with the swap sheets. Just don't forget to network.

Unless you are on a second floor weight itself should not be a huge problem but any decent machine will be over #1000 lbs. Even a manual machine will exceed that. Do expect to have to employ the services of a rigger / machine tool installer.

As to actual space taken up a CNC lathe isn't going to be that much worst than a manual lathe. It could be even better as there is a reduced need for human tenders. In any event if you expect ot automate as I understand it you will be turning bar stock which implies a long area allocation to the left of the machine (most instances).

I live pretty close to Houston and I would imagine that there are some used tool dealers in a city that big. I may try the yellow pages.

It is certianly worth trying but you are likely to suffer a rather large mark up over what you could pay going the more direct route. The other thing to consider is a machine tool manufactures that might have used equipment hanging around due to customer upgrades.

As of now my maximum diameter on parts has been 1", actually 24.3mm, so a 1 1/8 thru bore would be great.

Well if using collets that isn't so great, that is with 5C collets. Even so you should be able to find the stock you need to run you parts.

Is it possible to convert a collet closer to function automatically?

Yep, infact this is what I imagined you where looking for, that is an automatic solution.

What does CHNC stand for? Thanks for the info. James

CHNC is a Hardinge lathe.

One thing you need to keep in mind is that going the CNC route to build your own parts is not an easy thing to do one littel experience. Do expect a significant learning curver and allow for set up time.

Dave

[jdholbrook]

Dave,
Thanks for the excellent reply.
I'm guilty of posting before doing my homework!
However in my defense I didn't know what homework I needed to do until I read the replies to my original post.

In looking at tool dealers in the Houston area I found a CHNC for $3000!
I will go look at it when I get back from this business trip.
It weighs in at 1790# so should be doable as far as getting it moved in and setup.

When you mention barstock I envision 8 foot sections. My original vision was to use 2 to 4 foot sections but yes the 1 1/8 ID of the 5C collet will be enough for everthing I've designed up to this point and in the forseeable future.

My experience level can be summed up as follows.
I bought the Taig in a CNC ready state. Bought and installed the steppers. Bought a board from Xylotex, wired and installed it in an enclosure. I built an enclosure for the mill as well as a flood cooling system. It has since been pretty busy turning out parts and I am very pleased with the accuracy of the unit.
I also have the Taig lathe which has seen many hours of use turning out parts by the hundreds.
Everytime I set down to make a batch of 50 or so parts I mumble the words "Wish I had a CNC to do this"

Below is one of the parts I make.
It's in two parts. THe base and the tube.
I turn the base on the lathe then jig it on the mill where I drill the holes and later tap the threads by hand.
The tube is produced on the lathe and both are mated using Loctite 609.

I now get the base produced at a cost of almost $4.00 each in quantity 500.
I estimate the tube costs me less than $1.00 to make (I figure paying myself $20 per hour labor cost)
I figure if I could use a CNC lathe to produce both parts I could drop my cost down to $2.00 or so for the pair. That means a $3.00 per pair increase in profit. How many would I have to make to pay for a CNC lathe?
THat doesn't take into consideration the other parts I want to make but am holding off due to the high cost of getting them machined or the fact that the final product will be exactly what I want and not something that "will do" (My last order was not exactly what I wanted and had to have them made again by another place)
This post is getting long.

What kind of controller would a CHNC be using? Will it take G codes? Can I upgrade it to a controller that would work with Mach3? Geckos or something?

Thanks

James

[Karl_T]

Originally Posted by jdholbrook Dave, What kind of controller would a CHNC be using? Will it take G codes? Can I upgrade it to a controller that would work with Mach3? Geckos or something? Thanks James

The CHNC , short for High precision CNC, has been made for many years and has at least four generations. The original machines with the Allan Bradley control are going for peanuts. Of course, condition of the machine is everything. These machines were built to run 24 hours a day for years. Holding 50 millionths tolerance is standard stuff for one in good shape.

I've seen newer machines with Fanuc and Seimans controls. You could get one of these ready yo use. But I doubt if you'd find one for only $5K.

I don't know if Mach3 will do a turret, you'd best ask on their NG. As to drives, the X and Z are standard brush type servo motors, easy to upgrade to a gecko or many other drives. I'd replace the spindle with a VFD and three phase motor. I used a 7 1/2 hp 3 phase motor and VFD from automation Direct on my machine.

Rebuilding a machine control is a BIG job. If you just want to make parts, I'd suggest you buy a machine in running condition.

There's a fellow in Dallas that has been trying to sell CHNCs on Ebay. I think he just had a pair up (one for parts) that went down without a bid.

karl

[titchener]

I don't know where you're located, but if close to Ohio, check out ebay item 7574914020 , a servicable looking CHNC for around $4500.

Paul T.

[jdholbrook]

Paul,
I marked that one to watch.
I live in Texas and have no idea what freight would be. I also saw that he's got "best offer" on it. I may put an offer and see what happens.
I found one in Houston for around $2900 at a used equipment dealer that I will go look at when I get home.
I also found another one on ebay.
Item #7577186286
Shows a GE Century 550 control. Is that one that will have to be junked?
It's in El Paso Tx so not that far of a drive.

Thanks
James

[titchener]

One thing I meant to mention in my earlier post- the "pass-thru" maximum size on a 5C collet is 1-1/16", not 1-1/8". You can get 1-1/8" 5C collets but the stock can't pass thru the back end of the collet on them.

Regarding the older GE controller, I don't know anything about those, but if its still working and will do the job, what the heck. However, even if the control is working I would be prepared to retrofit it if it takes a fatal dump down the road, I would recommend Mach3 using Gecko drivers. They recently added lathe support to Mach and it looks pretty nice.

Paul T.

[wizard]

Originally Posted by Karl_T T. I've seen newer machines with Fanuc and Seimans controls. You could get one of these ready yo use. But I doubt if you'd find one for only $5K. I don't know if Mach3 will do a turret, you'd best ask on their NG. As to drives, the X and Z are standard brush type servo motors, easy to upgrade to a gecko or many other drives. I'd replace the spindle with a VFD and three phase motor. I used a 7 1/2 hp 3 phase motor and VFD from automation Direct on my machine. Rebuilding a machine control is a BIG job. If you just want to make parts, I'd suggest you buy a machine in running condition.

Karl points an important point, it woulld be best to find a machine in working order!!!

On the other hand the machine is a good platform for rebuild. As pointed out it is not a task to be taken lightly.

With any used machine tool do demand to see the unit working if at all possible. Further mechanically inspect the machine completely. If you are not sure about how to go about that then get help from somebody with experience. The age of the machine doesn't mean much mechanically, more so how the unit was used and maintained will dictate mechanical condition. Inspect Inspect Inspect!!!

Electrically age is everything, the older the control the more problems you can expect. Some of the older electronic CNC controls are not worth repairing in any manner shape or form. Note what controller the lathe has and research support and issues with it.

Do not get to wrapped up in a specfic Model lathe there are many options out there. Hardinge is just one example of a machine tool builder and it could be argued that one of their slant bed machines might be a better investment.

There's a fellow in Dallas that has been trying to sell CHNCs on Ebay. I think he just had a pair up (one for parts) that went down without a bid. karl

NOTE:
PC based CNC controls are nice but you best look closely at just what they will support. That is if you expect to do a conversion. The other option is to buy a full blown CNC control from a vendor and install yourself. Either of these avenues are "time sinks". On the other hand you could end up with a machine that is nice for a fraction of the cost of a new machine.

Also note there are other lathes, or where, that used Hardinges 5C spindles. Frankly I forgot the name but you might find something like that while looking around.

On another note my Grizzly catalog came in yesterday and they now have a CNC mill for $20,000. I would not be surprised to see lathes as cheap or cheaper in the near future. The big issue is that you really want a machine designed from the gournd up for CNC work.

[jdholbrook]

I am looking into Tool Turret macros in Mach3.
It would not be a problem for me to design and build a seperate microcontroller (stamp or PIC) based controller to operate a turret. (send it a position number and wait for the ack)

Would something like this ebay item # 7575904450
be suitable?
My concern is that something older would not be able to hold the tolerances I'm looking for. Typically I hold my parts to 0.01mm.
If I had to rebuild it I'm sure the investment would go up quickly.
Can they be adjusted like a manual lathe?

I was looking to get something this month but after this post I'm going to wait another month or two and do more homework.

Thanks
James