Post By fizzissist
Post By Milflyer
This isn't lathe related, but I posted this here because I know the members here have first-hand experince with top quality machinery and can make an informed suggestion.
I would like to know what the best small surface grinder is. The average size job I would run on the surface grinder will not have a dimension larger than 3 inches / 75 mm. However, I am looking for consistent accuracy of 0.0004 in / 0.01 mm.
The main job for the grinder would be to surface grind rails for the aperture of a movie camera (where the film runs and is exposed). The rails are very important because they control the side to side steadiness of the image.
One of my customers runs up to 400,000 feet of film through each camera each year. The film cuts groves in the nickel plate on the rails, so I would need to strip the plating, grind and then send out to be re-plated.
Also considering plating with TiN or other such coatings over nickel or hard chrome to increase abrasion resistance even further. Anybody here ever had TiN coatintgs put on your custom parts or tools?
I would think that any reputable name US or german made (ELB) or Scandinavian (Jacobsen) grinder would be able to hold .0001 in the size envelop you mention, as new. So the big question is ging to be what condition the grinder is in, more than name brand. A grinder can only grind as true as the ways. And then that factor will be modified by the operators knowlege and experience in running it.
Taft-Pierce has a high reputation for the small grinders in the 5 x 10 size, and they built some of the best metrology and reference tools at one time, so they knew what they were doing. Reid, and Brown & Sharp are other good names. Personally, I'd look for a 6 x 12 or 6 x 18 B&S micromaster, but that may be bigger than you want if space is a limitation. In new grinders, Harig makes small manual or auto machines with an excellent reputation. I've run some of the manual machines and they are convenient but seem a little light, but they are accurate. They also tend to be pricier used than machines that IMO are more substantial (Such as micromaster).
Once again, the big factor is going to be condition. If it's a used machine, don't take the seller's word for it if you have to hold tenths. Inspect it yourself. many sellers actually believe their grinders are in excellent shape because they naively indicate the chucks and naturally always get a 0 - 0 reading. You need to use a surface plate and straight edge to check the table ways. For the work you propose, check also that the spindle is dead square to the X ways.
You might look for an old Sanford benchtop surface grinder. These are small machines that are pretty rugged. They can only do small work - having a chuck of around 6" x 4". If you find one in good shape it should be able to do the job.
Here is a thread on the Sanford:
Sanford Surface Grinder Thread
The Sanford is a joke compared to a Taft Pierce...kinda like comparing a US Burke mill to a Deckel !
I thought I might get a dope slap on that one
I've never seen a Taft-Pierce surface grinder but I do have a beautiful double angle sine plate from them ... yes, I agree they are the real thing.
Given what he is doing, it seemed like the Sanford would suffice.
Risking another dope slap - what do you think of Chevalier grinders (nice choice of names for a Taiwan company - sort of Frence/Swiss sounding)?
Mitsui,Okamoto, Harig, Chevralier, just as long as it is not worn out would do that job. I like Harig's with tool steel ways and auto axis controls. (I have one and I like every thing I have, just ask me ) Hand grinders get old real fast. Get an automatic if you are going to do any serious grinding.
BTW, I don't know if this would be a similar thing but I used to work in the tape drive industry (big tape drives for big mainframe type computers) and all the machines used synthetic sapphires or bonded then ground carbide for the tape path guides. I guess they had problems with stuff going south if they didn't use something very tough in those areas of the machine.
Thanks for the replies. I will do some research on those machines.
Re: Tumbleweed's post, the manufacturer (ARRI) did go with sapphire roller guides on the 4th generation camera version. I usually work on the first and secon gen cameras. However, some technicians I have talked to told me they have had to take the sapphire rollers out due to sqeaking.
The cameras have to run very quiet (for shooting sound scenes). The new ones run at about 20dB, the older ones 25-28dB (A). I don't know why they just used nickel on the older rails. Seems like a harder material would be better. I think the new version rails are hard chrome.
I assume a manual grinder means that you have to crank the wheels for each grinding pass?
Correct you are. Fun for about two passes, then it gets old. Being able to control the feed rate is a big advantage in any type of machining. Hard nickel or chem nickel is reasonably hard, but the chrome would be a bit better. I think they went to carbide scrapers before the recording head to reduce noise, but I am not sure. I was just a parts inspector, not a design guy.
I assume a manual grinder means that you have to crank the wheels for each grinding pass?
For a fan of late model Schaublin machines, I know where there is the small surface grinder that would excite you. An Alb Tripet, made in Switzerland. Pristine, appears as new...complete with current model Heidenhain DRO...and it does have auto table travel functions I believe.
Last I talked with the company, they had visions of using it, but I seriously doubt they ever will, so it may become available in the next 6 months.
If you can find a nice 5x10 Taft Pierce, and it first your budget, by all means get it. They are fantastic machines. They seem to hold value very well, which is a bad thing for a used machine tool junky like myself.
Does anyone know where to buy grinding wheels for a sanford benchtop surface grinder(4.x3/8/x1/2)?
Jorge, you might look into the DLC/diamond-like coatings. IIRC I read that DLC'd titanium wristpins are being run in some race engines directly on an unbushed steel rod.
They can vary the coatings for hardness and lubricity.
If you can find a small Jones and Shipman or a Jacobsen either of these will do all you could ever need, A Brown and Sharpe Micromaster would be nice but is physicaly much bigger. we have all three in the lab and allthough a little weird in its controls the Jones and Shipman is the easiest for small work and dead true. For the sort of work you describe I would not worry about the manual versus mechanical systems. I doubt that you will be doing more than one piece at a time so it is not really an issue. Regardless of what you buy remember that grinders need a lot of TLC and make a terrible mess, hydraulic actuation systems are a real bear for leaking particularly if used infrequently and in themselves can be disgusting shop poluters.
With regard to TIN coatings I had the steel pallets of a Graham Deadbeat Regulator clock I built 15 years ago coated and allthough they work with a hardened (62RC) steel escape wheel they were still as new 2 years ago when I cleaned the movement. For those mathematicaly minded among us this means about 471,500,000 actions without any apreciable wear.
Curious about the squeaking...20 to 25dB is a huge difference too...all because of the sapphire rollers (is this an Arri?)? Gotta be more to it. Like too much contact area along the rails? Or a slight misalignment when the rails are rebuilt,,,,suggesting that the gate and rails need to be matched?
Wondering if the sqeaking is the sapphire rollers themselves? Small concentricity variations buckling the film when the film width falls on the upper tolerance limit?
As to coatings, there's a lot of really great coatings you might consider in addition to TiN or TiCN....Might be worth checking to see if Korolon might work(maybe not this application, but I'm curious)?
There's also SIALON, a high density, high wear resistance engineered ceramic that could be looked into.
Never mind me, just throwin' ideas out there!
The Jones & Shipman 540 is a nice little toy grinder. J&S = top quality, but probably little known in the US. Maybe safer with a new Chevalier than an old, albeit once-good-quality dunger?
I would be looking for more info on the plating involved, would have thought hard chrome would be preferable to nickel etc. Hard chrome is a specialist industrial coating, it has nothing to do with the normal "show" chromium type stuff.
BTW, I would have thought that the importance of such a camera part being right in the overall cost/scheme of things - wouldn't you just buy a new part? Replating, grinding, trying to get square corners, avoiding cracking the plating etc what a hassle (and cost)!
BTW #2, no doubt nice equipment to work on, I have never seen one, but sounds like precision machinery?
OK, I'll go away. [img]smile.gif[/img]
Neither Mr. Jones nor Mr. Shipman nor Rolls Royce
Brittish Aerospace, Cosworth, Maclaren, Hilger and Watts, Taylor, Taylor, Hobson and Cook, the Royal Arsenal and countless other best in the world operators consider them "toys" so I am somewhat surprised you would.
Consider yourself rebuked Sir!
Since this is probably for an Arriflex super16, which is a german camera, he should probably be looking for a german grinder....like an Elb?
Btw....J&S is rather well known in the U.S.
The J&S Range are far from "Toys" ... you just can't educate some people
Furthermore, there are usually as many J&S machines on eBay UK as on eBay US / Canada ...
and FWIW, a very nice small machine built to a high spec (and price US$12K) is the British built EXE 1308 Precision Surface Grinder ... [img]smile.gif[/img]
Now I hear you guys say "Who" ??
... more info available if required.