Cheap vs expensive spin fixture/punch grinder/spin fixture

[Doozer]

@DouglasJRizzo - So you were "content" with an inexpensive one? What would you say that it's limitations are and are you glad that you didn't spend the extra $$$?
I think I'm in a similar boat to your mindset at the time...

Limitations of a cheap model are the centering accuracy of the vee block.
on a regular single slide model, you get the centering accuracy that it
is made with. Then their is angular coaxial accuracy, or how parallel
are the working surfaces of the vee block to the axis of rotation.
And then there is roundness of the rotation, a function of the bearing
races, and balls.
Another way to say it, how straight (non tapered) do you want your part
and how round do you want your part and how symmetrical do you want
the features on your part.
If the accuracy of these things is not needed per the specs your parts
are required to have, or you do not mind the aggravation these
inaccuracies cause when setting up a part in the tool, then you may
be ok using a cheap one. People who own a good one know how
much of a benefit it is not fuking around every time you use it.
If you buy cheap all the time, you are usually walking around
frustrated all the time. I have learned there are many other things
in life that can frustrate you, and for me, owning cheap tooling is not
going to be one of those reasons. It is called WISDOM. Some people
never acquire it.

-Doozer

 

[DouglasJRizzo]

@DouglasJRizzo - So you were "content" with an inexpensive one? What would you say that it's limitations are and are you glad that you didn't spend the extra $$$?
I think I'm in a similar boat to your mindset at the time...

Yes, quite content with it. I was (and still am) using it to size up arbors, pins and cutters when I need something that is a little odd in size. I also use it to obtain a ground finish on some smaller parts. For the few dollars I spent out of a tool catalog, it has paid for itself many times over.

 

[Doozer]

Yes, quite content with it. I was (and still am) using it to size up arbors, pins and cutters when I need something that is a little odd in size. I also use it to obtain a ground finish on some smaller parts. For the few dollars I spent out of a tool catalog, it has paid for itself many times over.

Does it have any if the limitations that I spoke about, or ?

-D

 

[stephen thomas]

Have a Suburban mastergrind here, but hardly ever use it out of fear of getting it dirty.
Mostly use an accurized Taiwan spindex. With coolant.
But that 2 way set that Doozer linked looks interesting for non centered work.
(Looks like you have to pay attention, some listed as 2 way don't appear to be.)

I'm guessing from the thickness of the case that it is probably a single ball bearing style, like Harig?
As opposed to Suburban's double row IIUC.

 

[Conrad Hoffman]

I was fortunate enough to pick up a lightly used Atco Punchmate #1. I wouldn't dream of hitting it with anything; why would you? It's a great problem solver for grinding, light machining and inspection. There are all sorts of things I wouldn't have been able to do without it. I don't know anything about cheap ones, but I suspect a new cheap one would be better than many/most used ones. They get grit in the bearings and aren't made for abuse Many/most can't easily be rebuilt. Now that I know how useful they are, if I didn't have one, I'd buy a cheap one and keep looking for a clean used decent one. BTW, does anybody know who made the first one and who copied who and who made them for other labels? There seems to be a lot of similarity between the various makes and vintages.

 

[DouglasJRizzo]

Does it have any if the limitations that I spoke about, or ?

-D

It's "good enough" for spinning tool shanks and pins, and such, its accuracy is fair. It's NOT a Suburban Master Grind, for sure.
Its motions are not smooth or fluid, it's construction and fit/finish - very basic.
For things that are .002" or so - no problem. Any tighter, I'd best look elsewhere.

 

[eKretz]

No kidding. I have ball pein hammers from 4oz to 32oz. Brass hammers of various weights. Rawhide mallets. Hard plastic mallets. Deadblow mallets. A couple of jeweler's hammers rather under one ounce. And that doesn't count carpentry hammers and a cobbler/bookbinder hammer, which I don't use in the machine shop. Or the 2lb drilling hammer I mostly use with an anvil. Etc. etc.

I don't even want to think about it. I gotta have close to 40, I bet. And a Grind-All, and a couple of those plain bearing 5C spin/indexers. And... Stuff everywhere.

 

[Doozer]

It's "good enough" for spinning tool shanks and pins, and such, its accuracy is fair. It's NOT a Suburban Master Grind, for sure.
Its motions are not smooth or fluid, it's construction and fit/finish - very basic.
For things that are .002" or so - no problem. Any tighter, I'd best look elsewhere.

.002" ? ? ?
Grinding things I usually want less than .0002".
Wow, cheap really is cheap.

-D

 

[DouglasJRizzo]

.002" ? ? ?
Grinding things I usually want less than .0002".
Wow, cheap really is cheap.

-D

It is, and again, for the little I paid (under $200) it's more than adequate for the light use it sees.
I do have access to OD and ID grinders if I need tight tolerances, but my lathes are usually sufficient to hold tenths.

 

[Doozer]

Well that is actually good information to know
for anyone contemplating purchasing an import model.
Thanks.

-D

 

[stephen thomas]

For things that are .002" or so - no problem. Any tighter, I'd best look elsewhere.

How closely have you inspected it?
What motions intrinsic to the fixture are not reliable to less than '.002" or so'. And does that imply +/- .001" or +/-.002"

Presumably a workpiece is placed in the Vee, snugged up, the lateral and vertical distance adjusted with an indicator or gage blocks, everything locked, and then spun to some arc, possibly including 360+ deg.

Is the Vee alignment poor such that a cylinder (pin) diverges (angular) both vertical and horizontal from the rotational axis?
(And?) or is the axis of rotation not parallel to the base nor perpendicular to the face/back?
IOW, could the tool be "accurized" with some selective grinding? depending how you value time? or is there something worse at "play" in the movable functions?

Is the fixture just plain sloppy - things wobble after tightening? Does snugging cause the components to deflect unreliably? Can the bearings really be that bad? I mean a plain bearing Chinese spindex with the damper adjusted will rotate within a couple/few tenths round. (though it cams back and forth)

Thank you for any further insights.

 

[Doozer]

How closely have you inspected it?
What motions intrinsic to the fixture are not reliable to less than '.002" or so'. And does that imply +/- .001" or +/-.002"

Presumably a workpiece is placed in the Vee, snugged up, the lateral and vertical distance adjusted with an indicator or gage blocks, everything locked, and then spun to some arc, possibly including 360+ deg.

Is the Vee alignment poor such that a cylinder (pin) diverges (angular) both vertical and horizontal from the rotational axis?
(And?) or is the axis of rotation not parallel to the base nor perpendicular to the face/back?
IOW, could the tool be "accurized" with some selective grinding? depending how you value time? or is there something worse at "play" in the movable functions?

Is the fixture just plain sloppy - things wobble after tightening? Does snugging cause the components to deflect unreliably? Can the bearings really be that bad? I mean a plain bearing Chinese spindex with the damper adjusted will rotate within a couple/few tenths round. (though it cams back and forth)

Thank you for any further insights.

Holy cow!
Stephen, you must be an engineer too.
We are in the group of the most annoying
and socially awkward people on earth.
Nice to know you.

-Doozer

 

[xavier2089]

Have you noticed any change of height in the z-axis of the spin fixture with relation to the rotational axis since your ownership of the tool, with growth of the main body caused by improper machining before heat treatment? Is the main body "fine grained", with uniform grain sizes under 10 microns in diameter as measured in a controlled metrology room under a microscope at 20 degrees Celsius? I'm just kidding...

@stephen thomas & @Doozer - Good point, I should have framed my questions more specifically around the runout of the bearings and any angular divergence from the axis of rotation. I just didn't think anybody would bother checking for me, but I too would like to know. I don't have specific tolerances in mind, per se, but I would currently "be happy" with roundness of better than + or - 0.005mm. For now anyway.

It looks like, from the picture Doozer first posted, that you could "accurize" (I'll go with US spelling haha) that model with some regrinding. That is, everything except for the bearings, without too much trouble. And if stephen thomas is claiming that a plain bearing import spindex can have a few tenths roundness ( I have never used one so again, have no idea and will trust in your advice), I imagine that the model Doozer posted would surely have something better than 0.002"!?

Thanks @DouglasJRizzo, that insight of 0.02" is good to know.

After swearing that I saw one once in one of Stefan Gotteswinter's videos, I found one with him using it

Given that he's rather particular with most of his purchases, I'm guessing that the bearings are not too bad. Just FYI, I'll go with the import. If I ever need better accuracy then I'll bite the bullet later.

Thanks again everyone for your input!

 

[???]

For a cheap spin fixture with no offset I just use a straight shank ER tool holder with 2 sealed bearings on the shaft in a precision V block. Set it up on the surface grinder with a O-ring to drive it off a motor controlling speed with a bench power supply.

 

[Doozer]

Thanks @DouglasJRizzo, that insight of 0.02" is good to know.

He said .002" not .02".

-D

 

[stephen thomas]

Holy cow!
Stephen, you must be an engineer too.
We are in the group of the most annoying
and socially awkward people on earth.
Nice to know you.

Well i have always appreciated your posts, too!

No papers here, work life was as a carpenter, self taught machinist to make all the cutting tooling and fixtures used in my niche millwork shop. And for other shops and niche industries including a little bit of medical
Since 70th winter i'm a professional ski instructor past 2 years.
Hoping the knees hold out
If it was possible to convince my wife to move to Chile or NZ during US summers, i could finally attain my fantasy as a teenager of being a full time ski bum

smt

 

[neilho]

Chile is a pretty cheap place to live, getting there? not so much but better than NZ.

 

[Ox]

Chile is a pretty cheap place to live, getting there? not so much but better than NZ.

We saw a lot of homeless camps up all over when we was in Santiago a few months ago.
Many right out along the through-fare highway. So, if there is that much in common with The City By the Bay - along the 6 lanes, I can only imagine how much there is further elsewhere?

I did not see that in Buenos Aires.


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I am Ox and I approve this here post!

 

[neilho]

Yeah, looks homeless to us, but in Chile, esp in the country, there's a lot of peasantry. Not a pejorative, BTW, just people working and living on a lot less than us. They get more respect and services too. Universal health care, for instance, and great bus systems. Buenos Aires is a big sprawling city, seems likely it's there, too.

Sure is nice to get some summer in the winter too, eh? Where'd you get to in Chile?

 

[Ox]

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Think Snow Eh!
Ox