Why did jig grinders replace jig borers?

[jscpm]

I never quite understood why jig grinders replaced jig borers. Grinders definitely generate more heat, which is bad.

I guess the borer does not have the problem that you have to deal with cutting tool geometry. And you can do outside diameters.

 

[Garwood]

Jig borers got replaced with CNC mills, not jig grinders.

 

[implmex]

Hi jscpm:
Back in the day, when I was a greenhorn apprentice, the common "precision" hole making machine was the turret mill with all of its obvious limitations.

Getting truly accurately positioned holes on a turret mill was and remains a crap shoot, so for anything that needed to be better, a jig borer was the ticket.

But getting holes of excellent geometric fidelity is harder on a machine that tears away a relatively large chip with a positive rake tool than it is on a grinder which makes many small chips with negative rake cutting edges on a tool that can be balanced, can be dressed to run perfectly concentrically, and can take tiny chips without skating over the workpiece.
It can also cut hardened materials in a way that could not be otherwise processed back when jig grinders were precision kings.

I started my apprenticeship back when Valenite was the principal supplier of carbide tooling and they were awful compared to the modern offerings, so hard milling and hard turning were fantasies.
There was no CNC in regular use and there was no wire or sinker EDM in widespread use...these were highly exotic processes fit only for the Gods.

So for precision holemaking in known locations, the jig grinder was king, and when it came to hard machining and exquisitely accurate hole geometry too, the grinder had the advantage over the borer.

Fast forward to the widespread adoption of the CNC mill.
Now the positioning capability of the borer could be approached by the mill, but the ability to process a hard material still could not, so the grinder remained relevant in this niche after the borer became redundant.

Now we have very much more efficient ways to make a dead nuts accurate hard hole, and we can make long ones and short ones and blind ones and through ones to a level of precision routinely, that takes a lot of skill to achieve with a jig grinder.

So they've both become obsolescent.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[TGTool]

I ran the toolroom jig grinder back in the day, and another feature we used often in diemaking was tapering holes. Die blocks needed clearance below the land so slugs didn't build up and blow up the die. Once the hole was ground to size and location for the punch, we could set the machine to start tapering below that. Wire EDM took over some of that functionality but it couldn't match a ground finish. It was a lovely machine.

 

[Robert R]

The death of the jig grinder has been greatly exaggerated.

Jig Grinders at Moore Tool: Precision Machining Technology, Precision Tools

Moore Tool manufactures a complete line of high-precision machine tools and measuring machines. Our products include jig grinders and accessories, fsp high-speed machine systems, rotary tables, precision stages, abrasive grinding wheels, and custom machines. We also provide jig grinders...

mooretool.com

Details:
500 series grinder

https://mooretool.com/pdf/F-1603%20Rev.%20F%20-%20500%20Series%20English.pdf

1280 series grinder

https://mooretool.com/pdf/F-1690%20Rev.%20G%20-1280%20Series%20English.pdf

 

[jscpm]

Well, the jig grinder is definitely still widely used. Moore only makes grinders now, not borers. Also, of course, SIP and Mitsui Seiki both make jig grinders as well as jig borers, although I guess they probably rarely sell the borers. So, I guess the borers are not completely dead.

I don't know why Garwood is saying CNC mills replaced jig borers. As far as I know, all but the most specialized CNC mills only have IT8 tolerance which is nowhere near what is necessary for precision fits.

 

[DDoug]

I don't know why Garwood is saying CNC mills replaced jig borers. As far as I know, all but the most specialized CNC mills only have IT8 tolerance which is nowhere near what is necessary for precision fits.

CNC mill does the roughing, then heat treat, then Jig grinder.

 

[jccaclimber]

I don’t remember the brand, but I was in the tool room of a fine blanking company a few years back and noticed a CNC jig grinder. I asked about it and the response was that they were trying to get a second one because only having one was backing up their shop.
This was the same group of guys who talked about the difference between dead sharp and a couple micron edge radius making all the difference in the world, so they aren’t working in the same world as me.

 

[TGTool]

I can only imagine the fun of having an NC jig grinder. I never had to do contours on the jig grinder, but I can see a need for it on complex, high precision parts. And the business of setting up radii, angles, and tangents where the tolerances are minuscule and the opportunities for screwing up abundant is a recipe for ulcers and hair pulling. I already have almost none left. Enter NC control for machine movement. No more rotary tables and all the rest. Whee.

 

[???]

A salesman will always tell you his latest greatest machine can replace your current machine and then some. I worked as a toolmaker for a company with state of the art CNC machining centers hard machining warm forge dies to 0.003mm tolerance, we still had a Hauser jig grinder.

Ran a Moore jig grinder in South Africa for a medical company, I've worked around the world on the latest and greatest (According to the sales rep) and the Moore is still hands down the best machine I have ever worked on for high precision. A fellow toolmaker decided that the needle point mold inserts for intravenous drip connectors could have the locating holes spark eroded, if it wasn't for the Moore the job would never have been fixed. 16mm diameter inserts into a 60mm deep hole in 56 RC tool steel prior to hard machining cutters. A walk in the park on a Moore.

A rule that I use on press tooling is up to 100 000 holes ream the die hole, up to 1 million wire EDM and over 1 million jig grind.

 

[AD Design]

Not much to add to what others have posted. In the 80's a Moore jig grinder was SOP for stamping die work that had come back from HT in a hardened condition. HT would often grow/shrink/warp the plates and throw locations off, not much but sometimes enough to make a difference. The slight scale from HT was considered worthy of being removed, WEDM scale was also considered something to remove. For location, size control, die taper, and scale removal the jig grinder was the simplest method of dealing with all four. There were also a couple of shops I worked at where the owner felt a WEDM hole (also in shop) wasn't quite as round/good as a jig ground hole. I've also made a few (very few) heeled punches that couldn't be ground any other way than with a jig grinder or a conventional (electrode) EDM. The jig grinder was much faster. I'm nobody to evaluate what a WEDM is capable of now but that's what we did in the 80's-90's in die shops. I liked using the jig grinder with CBN mandrels, much cooler temps than mounted abrasive wheels.

 

[implmex]

Hi AD Design:
A jig grinder will still produce a better hole for an application in which you are going to stress the corner, (like the die opening in a punching station) than a wire EDM will, (especially in carbide) but the gap is steadily closing and the quality of a wired hole is getting very good indeed.

However, the major benefits to the wire over the grinder are pretty obvious:
1) Your desired shape need not be round and the level of skill needed does not really change if it's not...unlike with a jig grinder, even a CNC jig grinder.

2) You can make ridiculously unfavourable aspect ratio features to an excellent level of precision, and you can make very small corner radii easily.
A different skill and knowledge set is required, and it's less experience dependent...I can whisker off a tenth a side in a 1/4" diameter hole 6" long just by changing the wire offset and pushing the green button again, and with only a few caveats, it will do it reliably and accurately, and I don't need to hire vast, almost unobtanium skills and experience to make as many of these difficult and super accurate holes as I may want.

3) The setup to put features in their proper relationships is a small fraction of what's needed to grind, as soon as the features are not round.
On a wire I can do things easily that are impossibly hard to do on a grinder; as an example I've been making gears for the robotics guys lately, and I can get the pivot bore concentric to the pitch circle within a tenth without breaking a sweat simply by wiring both bore and teeth in the same setup.
I can also get the tooth form and tooth spacing to a similar tolerance ridiculously easily and I can do it in a 6" tall stack of gear blanks with internal corner radii of 0.010".

So yeah, those who claim a jig ground feature to be the best, have some valid points, but wires are getting awfully good, and they're pretty easy to use too.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[AD Design]

Hi AD Design:
A jig grinder will still produce a better hole for an application in which you are going to stress the corner, (like the die opening in a punching station) than a wire EDM will, (especially in carbide) but the gap is steadily closing and the quality of a wired hole is getting very good indeed.

However, the major benefits to the wire over the grinder are pretty obvious:
1) Your desired shape need not be round and the level of skill needed does not really change if it's not...unlike with a jig grinder, even a CNC jig grinder.

2) You can make ridiculously unfavourable aspect ratio features to an excellent level of precision, and you can make very small corner radii easily.
A different skill and knowledge set is required, and it's less experience dependent...I can whisker off a tenth a side in a 1/4" diameter hole 6" long just by changing the wire offset and pushing the green button again, and with only a few caveats, it will do it reliably and accurately, and I don't need to hire vast, almost unobtanium skills and experience to make as many of these difficult and super accurate holes as I may want.

3) The setup to put features in their proper relationships is a small fraction of what's needed to grind, as soon as the features are not round.
On a wire I can do things easily that are impossibly hard to do on a grinder; as an example I've been making gears for the robotics guys lately, and I can get the pivot bore concentric to the pitch circle within a tenth without breaking a sweat simply by wiring both bore and teeth in the same setup.
I can also get the tooth form and tooth spacing to a similar tolerance ridiculously easily and I can do it in a 6" tall stack of gear blanks with internal corner radii of 0.010".

So yeah, those who claim a jig ground feature to be the best, have some valid points, but wires are getting awfully good, and they're pretty easy to use too.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

-The WEDM is one of the few machines I've never run but wished I had. I always find your posts to be informative and often entertaining. Thank you for a more current understanding Marcus.

 

[implmex]

Thank you for the very nice compliment AD Design.
Running a wire is one of those skills where it is very easy to get pretty good, but quite challenging to get to the very top, mostly because there is an expectation that you can hit ridiculous tolerances on nutso parts with ease and will NEVER screw it up..

Compared to chipmaking that is often very true, but as in most things, the devil is in the details and it can take significant amounts of misadventures before you get a handle on most of the common ones.

I have no regrets about diving into the EDM world...it's enabled me to make all kinds of weird and wonderful stuff and it's been good to me financially too.
I'd feel pretty crippled without one for the kinds of stuff I'm asked to make these days.

I got my first one in 2008, and didn't even know how to change the wire spool when I first bought it.
Wire was wasted and scrap was made before I gained confidence with it...much wire and much scrap!

I spent quality time with the manual and more quality time talking to the guy who sold it to me, but eventually I figured out enough to be dangerous.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[gustafson]

Well, the jig grinder is definitely still widely used. Moore only makes grinders now, not borers. Also, of course, SIP and Mitsui Seiki both make jig grinders as well as jig borers, although I guess they probably rarely sell the borers. So, I guess the borers are not completely dead.

I don't know why Garwood is saying CNC mills replaced jig borers. As far as I know, all but the most specialized CNC mills only have IT8 tolerance which is nowhere near what is necessary for precision fits.

Which cnc mills were those?
My point being you can make a high quality CNC do almost anything[compared to a manual anything] but you cannot overcome the vagaries of a cutting tool compared to a grinder.

I don't think anyone was implying a Haas was a replacement for a jig borer

 

[TGTool]

All the vagaries of vibration, expansion, cutting force, tool wear, experience, and others answers the noob question, "If I put a tenths-reading DRO on my mill/drill would that make it a jig borer?"

 

[Peter from Holland]

Not

So they've both become obsolescent.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Shop nearby recently updated its 25 year old SIP Hauser Jig grinder with a new Fanuc controle New motors drives scales and all A expencive operation (Machine was still to specs BTW Only the table had some wear which was corrected by stoning the table a few 0.001mm)
Those machines are so goddammed accurate on the XYZ In both colomns of the portal there is a air cilinder pushing against the top and base of that colomn to compensate for the weight of the moving head If head moves to the left pressure gets bigger in the left cilinder
Accurracy of 0.002mm over 1000mm
Lots of work for ASML/Zeiss

Peter

 

[AD Design]

Wire was wasted and scrap was made before I gained confidence with it...much wire and much scrap!

To borrow a quote: "In that place there will be weeping and gnashing of teeth".

 

[RC Mech]

I don't think anyone was implying a Haas was a replacement for a jig borer

What, you’ve never had a boss put a tapered grinding stone in a CAT 40 arbour and insist you run it around a mold core?

Jig “grinder” is more analogous but RIP that poor Tree VMC…

 

[art.h]

I never quite understood why jig grinders replaced jig borers. Grinders definitely generate more heat, which is bad.

I guess the borer does not have the problem that you have to deal with cutting tool geometry. And you can do outside diameters.