Precision Matthews PM45 Tram and a New Vise

[Ray C]

Well, I finally broke down and bit the bullet for a new vise. I got one of Matt's 4" units and after spending half hour getting the cosmoline off it, decided to tram the table and check the vise. If I have any nit about this vise, it's the cosmoline it was packed with. Took a good bit of oil and elbow grease to get it off!

Tram first: I wish there was something to tell you but, after 4+ years of good use (sorry about showing-off a grimy machine) the table is all but dead on and no different than the day I set it up. It's a 24" travel table and the middle 18" is dead-on in the X direction. The last 2" on each end of the table, it raises by 2 ten-thous (0.0002"). The Y direction was checked at left, center and right and everything is within 0.0002". That's pretty amazing in my book, as this machine has seen some use -although, I only take medium to light cuts as I do with all my machines to make them last.



The Vise: Wow! If it makes any difference to you (it doesn't for me) it's made in Taiwan and is absolute perfection. It has a swivel base and I usually don't use the one on my old vise. The grinding is perfect on this thing and for grins, it was checked on the granite with a TDI. I could see no height differences at all. I like the extra wide circular seating areas for strong contact and stability.




It fits very well on this table with or without the swivel base. After checking it in every important direction, everything was either dead on or within 0.0002" and believe it or not, the results were the same both with and without the swivel base. The swivel base is very low profile and I'll keep it attached for normal use. I could never dream of that with the old vise. Oddly enough (and yes, this is a personality flaw) I even checked the calibration of the degree marks. Of course, it's an "eyeball" measurement but, it was spot on when I checked at 15[SUP]o[/SUP] using DRO measurements and some trigonometry. The jaws line-up perfectly and I tried several times before and after clamping some scraps very firmly.




Now here's what surprised me... The actual jaws are Rockwell C at 65+ (I can only measure up to RC 65) and the ground surfaces of the cast iron measured 63-65RC. The metal sliding parts of the jaw are RC 30. For 250 bucks, you can't beat this thing! Also, it's designed so swarf does not get jammed-up in the way areas or on the screw. Very efficient design. I've known for a long time I needed a new vise and was eyeing Kurts and some others but, they're well over the $400 mark. I'm blown away by this thing. Happy camper here and when funds allow, I'm going to get another but, I'll be able to get by with the old one for a while. It's on the drill press now.

Now, I only wish I could use it... While working on the kitchen floor, I wrenched my lower back (working like a mad man) and had a devil of a time lifting the vise on the mill table.

Ray

 

[Ray C]

Hi folks...

It was brought-up off line that the TDI is not positioned in an ideal way for the measurements... Just want to point out that the stylus on that TDI is adjustable and even though the angle of the photos may not show it, the stylus is at a 45[SUP]o[/SUP] angle to the "horizon" of the part. Absolutely correct... it should be as close to parallel as possible but, 45[SUP]o[/SUP] engages well enough to register movement which is what I was really after...

Since the cosine of 45 is 0.707, so the measurements are off by 0.00014 thus, the measurements stated as 0.0002 are actually 0.00034 -still outstanding and everything was within that; meaning +/- 0.00017 which is a finer resolution than my DRO can read...


Ray

 

[Ray C]

And in the spirit of showing a more appropriate technique, here is shown checking the parallel block on the granite to make sure it's flat (though I know it is). Even though it's a Shars brand, several careful passes were made and it shows no deflection at all. This is a 0.0001 graduation TDI.



Also, I quickly rechecked half the mill table (I didn't want to unbolt the vise from the last readings so I could compare apples to apples)... -Zero deflection. And finally, as not to misrepresent the vise, I re-checked most of the previous measurements... No real difference from the first time... What was zero before, is still zero and the parallelism from the top to bottom of the rear (fixed jaw) and the bed area read within 0.00025" (where the last digit is estimated visually on the dial).



My apologies for showing a poor technique but, ever since I learned the stylus of that TDI is adjustable, I often don't bother to change the body angle when I'm more concerned about relative differences rather than absolute heights or thicknesses... I have two (actually three) TDIs setup by the lathe; one is setup for checking the front or back of a mounted shaft and the other is setup to drag along the top of a shaft. [The third one has a long makeshift stylus used to check inside bores]. The are all pretty-much adjusted to engage the stylus parallel to the "relative horizon" of the dimension I'm checking... Also, readings are always read by dragging (not pushing) the stylus. I'll show pics one day.


Ray

 

[Tony Wells]

LOL, you mean you iterpolated that 5th digit? Why? I thought you have a real indicator. Just kidding, of course, splitting tenths belongs mostly in the QC lab. One of these days I'll bring this back to your setup on the HeightMaster you have. A tenths reading indicator is not generally considered good enough to get the available accuracy out of one of those. Nor is a grade B gage block.

 

[Ray C]

LOL.... Estimated, Interpolated, Extrapolated... Do you say potato or do you say potato (hmmm, doesn't quite have the same zing when written, does it?)... I know what you mean though, all three words have distinct and very different meanings.

Yes, some pointers on the HM would be wonderful... As mentioned, I purchased it because of the price and hedging a bet I might need it some day. When that time comes, sure would be good to know how to get the most from it. Yeah, splitting tenths is silly in a home shop. It's taken me the better part of 5 years of self teaching, practice and equipment upgrades to get my work consistently inside half thou -and even then, a good blunder turns an optimistic smile into a straight-lipped self pep-talk of how to be better next time. If at first you don't succeed... teach yourself how to fix it!

Ray

LOL, you mean you iterpolated that 5th digit? Why? I thought you have a real indicator. Just kidding, of course, splitting tenths belongs mostly in the QC lab. One of these days I'll bring this back to your setup on the HeightMaster you have. A tenths reading indicator is not generally considered good enough to get the available accuracy out of one of those. Nor is a grade B gage block.

 

[benmychree]

What sort of hardness tester only measures up to Rc65? Besides that has it been calibrated against test specimens?

 

[Ray C]

The infamous Brinell scale only has numbers that translate up to RC 40. That's just the first one that comes to mind because I own one. I'm sure there are other methods too. Also, I would not be inclined to use an impact tester on a finished piece of work as, all such testers leave a small dent. As such, I use a rebound type tester and yes, I have compared it pieces of known material both commercial and pieces which I heat treated myself. I have a fairly precise heat treat oven and used certified steel with a very, very carefully controlled process. The results of the rebound tester are usually within 1-2 points of the calibrated metal and an average reading usually gives a dead-on number.

There's a particular model of Leeb tester I'd like to have but, the base price and cost of different probes is beyond my reach right now.


Ray

What sort of hardness tester only measures up to Rc65? Besides that has it been calibrated against test specimens?

 

[Tony Wells]

"infamous"? Ray, I can tell you haven't examined many MTR's on steel. If the Brinell scale weren't desirable, it wouldn't be there, but it's almost exclusively used on alloy steels.

And if you're going to declare accuracy on your tester, you should order some certified test specimens for it. I have some, but no tester yet, so not going to get rid of them. They're tested and marked to tenths of digit on whatever scale their for.

 

[Ray C]

I have a calibrated piece. I don't even want to tell you what I paid for it and won't say here in case my wife uses my computer and sees this. It was used on ebay and only had about 3 dings in it. Good enough for my purposes. It was bugging the heck out of me not knowing if the devices were in the ballpark... Much to my surprise, that simple rebound tester is pretty darn good.

From what I gather, most tests these days are done with Leeb followed by Rockwell followed by Brinell. Just about everyone specifies the method of test but converts the number to Rockwell because everyone has a good mental image of what the numbers mean.

Are you looking for a Rockwell unit for yourself or are you ok with a Leeb?

Ray

EDIT: Oh yes, Vickers... let's not forget Vickers. Also still used but not sure how much anymore. If anything, that's the infamous one -and by the way, infamous was meant in the way of "depricated" and not with negative connotation.

"infamous"? Ray, I can tell you haven't examined many MTR's on steel. If the Brinell scale weren't desirable, it wouldn't be there, but it's almost exclusively used on alloy steels.

And if you're going to declare accuracy on your tester, you should order some certified test specimens for it. I have some, but no tester yet, so not going to get rid of them. They're tested and marked to tenths of digit on whatever scale their for.

 

[Tony Wells]

I'd rather have a standard bench model Rockwell tester. It's a better fit for my parts. At least these days. Things could always change, but if I need a portable, I'll probably go with a Wilson or similar.