Hardinge TFB retrofit

After initially considering building a CNC lathe, from scratch, I decided that retrofitting an existing lathe would be a more cost effective solution. Having always admired Hardinge precision lathes, I decided that one of their 11” models would be perfect. I mainly do model engineering so I didn’t want a really big lathe but I wanted one that could produce precision work. After a bit of research it came down to either a HLV-H or TFB. Neither of these are cheap to buy but the TFB is less desirable due to the lack of screw cutting gearbox. This isn’t a problem for me as this feature will be replaced by CNC operation anyway.

After a lot of searching, I finally picked up a reasonable deal for a somewhat neglected TFB from ebay.

http://www.cnczone.com/gallery/data/500/PI2269.jpg

http://www.cnczone.com/gallery/data/500/medium/tfb2.jpg

First job will be to strip it all down, get the ways reground, replace the headstock bearings, clean it up and paint it. All the electrics are going to be discarded and I will probably try and sell them on eBay.

My current plans are:

1) Replace the 1.5 hp two speed motor with a 3hp inverter duty motor
run off a Hitachi VFD. I want the bigger motor for increased torque
so I can reduce the bottom speed below 125rpm.

2) Add precision ground ballscrews

3) Add bellows to cover the main ways and some form of shielding of
the lead screw.

4) DC or AC servos probably with Rutex controllers.

5) Interface spindle speed control and coolant to Mach3.

6) Build an automated tool indexer

I’ll keep you posted of further developments.

Well the lathe has been sitting in the garage for long enough and now it is time to dive into the conversion. My goals for this project are to produce a precision tool that can be both used for CNC use and manually via MPG handwheels for one-off and quick jobs.

This isn't a budget build but for around the same price of a nice used HLV-H that turns within tolerance (between $6500 and $10,000), I hope to get essentially a like new CNC lathe. The specs will be as follows:

1) Automation direct drive 400w AC servo on X
2) Automation direct drive 750w AC servo on Z
3) Mach4 with GRex
4) New 2hp baldor vector duty motor and 3hp vector drive (more on this later)
5) Ground ballscrews: X off eBay, Z probably purchased new
6) Super precision ballscrew bearings (both off eBay for $55 each)

This project is just as much a restoration as it is a conversion so will take a while to complete. The first step was to strip everything off the lathe so I can get the bed reground and refit the saddle and cross slide. Then I plan on scraping off the very poor brushed paint job, filling any bad scratches, rubbing down and spraying with a two pack grey enamel.

Below you can see the stripped down lathe. For the X Axis I picked up a very nice ground NSK ballscrew off eBay for about $220 (I actually got two). This is 16mm with 5mm lead and has never been used. The tricky part of this conversion is how to drive the X Axis. There just isn't enough room in the saddle casting to mount the ball-nut in the usual place. So after reading a couple of posts here on CNCZone I decided to extend the saddle at the back and fit the ball screw nut to the back of the cross slide.

http://www.cnczone.com/gallery/data/500/Diss2_s.JPG

http://www.cnczone.com/gallery/data/500/Diss3_s.JPG

Below is my initial mock up design for the X-Axis. I'll add more detail tomorrow.

http://www.cnczone.com/gallery/data/...xisDesign1.JPG

With the cross slide covers hidden:

http://www.cnczone.com/gallery/data/...xisDesign2.JPG

yeeeeh
finally a project to read

Nice going so far

Hi,
Are you familiar with the Gang Tool Lathe conversions for the Hardinge?
It's a very versatile configuration. You can load the toolbar with 6-8 tools
if you choose. From your sketches you are half way there.
Details can be seen at: www.omniturn.com/

Using the Vector motor & drive take care of spindle control for threading.
The X & Z only require 400W ac motors & drives.
The ball screws you bought are more than adequate.
I've bought new (old stock) Yaskawa motors & their SGDA
drives on E-Bay for under $125. ea.
For future reference:
If you are interested in a step by step instruction set for Hardinge
Spindle Bearing replacement SEE:
http://aafradio.org/garajmahal/Hardi...eplacement.htm

Yes I have seen the Gang tooling and omniturn setup. Its nice and simple but I am not a big fan, especially for the kind of work I plan on using the lathe for (model making). I often do work between centers which isn't possible with gang tooling.

Regarding the servos, it is actually a coincidence that I have just picked up 6 hardly used 750w Yaskawa amps and servos really cheap (less than the price of one sureservo setup!). I plan on using these with the skyko pixie step/dir converter boards. I also have some other 400w servos and plan to use one of these on the x axis if it works with my Yaskawa amp. If not, I will just use a 750w. Better to have a bit too much than too little!

Otherwise things are progressing steadily. Everything is stripped apart and the bed and saddle is ready to take to be reground. I am just preparing everything else for paint which is a tedious process. I don't have as much time during the summer so I don't expect process to be exceptional. However, my goal is to get everything painted and the basic stuff reassembled. I will also mock up some of the electrical stuff on the bench.

Quote:

---

Originally Posted by pstockley

Regarding the servos, it is actually a coincidence that I have just picked up 6 hardly used 750w Yaskawa amps and servos really cheap (less than the price of one sureservo setup!). I plan on using these with the skyko pixie step/dir converter boards. I also have some other 400w servos and plan to use one of these on the x axis if it works with my Yaskawa amp. If not, I will just use a 750w. Better to have a bit too much than too little!

---

Most Yaskawa drives can be set up to accept any input signal, including step & direction. Check your manual.

Darek

Unfortunately, mine are the analogue version not step and direction.

Whatever became of the conversion?

BW

Well, its a live but going slowly. Things have been stalled due to a house move.

Before the move, I finished the clean-up, sanding filling and painting. The paint is Sherwin Williams two part polaine B polyurethane enamel. This is the same paint used by Hardinge and is the best machine tool paint I have ever used.

http://www.cnczone.com/gallery/data/500/Paint_s.JPG

I sent the bed and cross slide off for a re-grind. The guy doing the job said he would never do another one! Apparently, because the dovetail is made from steel, he had a hell of a time with it warping due to heat from the grinding. In the end he had to result to taking a couple of tenths off at a time, leaving it for an hour to cool down and repeat.

Regarding, the servos I went back to plan B and bought 400w and 750w automation direct servos. The yaskawa's will be used for another project once I can get something to drive them. I am hoping future versions of the Smoothstepper will support analogue drives given that pixies are no longer available.

I still need to finish some home renovation stuff and setup my workshop so don't expect much progress until the middle of the year.

Nice update and beautiful paint job!

Given how much trouble your grinding fella had, I'd be tempted to want to check his work somehow before getting much further. Not sure how I'd do that though. Probably want to try to cut some chips.

Tell us more about your wonder paint. Is it hard to obtain? Where did you get it? How did you apply it? HVLP?

Best,

BW

I am not too worried about the grinding job. The guy is definitely a perfectionist and spent over 75 hours on it (not bad for $2200). If it is out then I can do some touch up with a scraper. Before the regrind, if you tightened the gibs to remove slop when the carriage was near the headstock you couldn't slide it to the tail stock end before it tightened up. Now it is smooth across the entire bed. Another good thing is that he ground the dovetail while still attached to the bed and at the same setting touched up the pads the headstock sits on. This should ensure the headstock is vertically parallel to the dovetail and also avoid me having to shim up the tail stock.

You can pick up the paint from any Sherwin williams industrial supplier. The only problem is they will only sell a minimum of 4 gallons. Needless to say, I will be using it for lots of projects in the future! I used 1.5 gallons on the lathe and will probably use another gallon or so on my Tormach machine stand. It isn't cheap (over $100 a gallon if I remember) but is way harder and more durable than any other enamel I have used in the past. I sprayed it with a standard spray brush, nothing fancy. The only thing to be aware of is it isn't very good to breath. I used an air fed mask that I picked up off an eBay store for $350. This worked great and is a lot more comfortable to wear than a typical canister type mask.

Nice work this. What came of it?

Nice work. I had run across a TFB lathe and was considering using it for manual and later converting to CNC for manual/automatic use. I'm a controls engineer by day, so the electronics wouldn't be a problem.

I'm alittle worried about having to rebuild the lathe from the get go, however. I know a hardinge is worth rebuilding, but at the same time I don't have the budget for a $3000-$5000 bed regrind and spindle change after shelling out $2k-$3k for the lathe. Maybe I'll save my pennies, sell some toys, etc.

One question: Are you going to retain the manual handwheel use? I've used HLV lathes in their prime and there is nothing like it, and I would be bothered if I couldn't get my hands on the controls once in a while! This will be paramount in a conversion that I do, but I think its possible without alot of headaches (Low cogging servos will be important to retain the "feel" and to prevent detent action. You are right to use Yaskawas, they are good motors. If you can I'd opt for the Sigma2 or especially Sigma5 series, but the older stuff is more easy to find on Ebay. Even sigma 1 motors are very nice. We've never had a yaskawa fail at my work. Another thing to consider is trying to score an old Delta Tau PMAC off of ebay. They will handle analog torque commands to your amps and can process G code I believe. I've used them, but never with G code as we mainly do work on assembly machines with custom purpose designed software. They can be a pain to set up but you will never have a performance problem with them. Having said that, Mach with a step interface is ALOT simpler!

One thing I like about this idea is that I was thinking of converting an old cheap american lathe or a new chinese lathe, but I'd hate to invest all the time into CNC conversion on a lathe that is not worth rebuilding (old cheap american lathe) or a lathe that will wear out for heavy use and has alot of subtle pain in the butt problems even when new (Chinese lathe).

With a hardinge, its worth having even a half worn out lathe to tinker with, worth converting to CNC because of the precision, and still can be rebuilt to bring it back true and it will be worth the investment.

I am also using my shop for hobby work and maybe someday prototypes and very small production out of my home. If anything went beyond that I'd sub out parts to a real CNC machine house anyway!

Thanks for inspiring me on an idea I already had, and I'll say great minds think alike!

Let us know how it goes.

BTW, does anyone have other ballpark pricing for grinding the dovetails on these? I'd hate to buy a worn out lathe and find out that you got lucky at $2k and other "machine tool" shops want $5k or more to do the job.

Also, did you find that any of the handwheel/gear bushings or anything else were worn out?

Thanks,
~ken