Benchmaster progress

[J Tiers]

OK, I've had this refurbished machine in use for a while. Now I even have a lamp on it to see the work better.

So now I have come to a realization:

I DON'T ACTUALLY LIKE THIS MACHINE!

After spending a good deal of time fixing it up, and having all the parts for it to be either vertical or horizontal, I just don't like it now that I have used it for a while.

So, I hear you ask, what's wrong with it?

This is. This is a view of the work from the normal operator position. The block is just set there to represent the work, no hold-downs.



The thing I do not like is that you cannot see diddly-squat under that huge head. This is with the cutter, a 1/4" end mill, in a collet. The belt cover is 8" wide, and the end of the cutter is only about 2 1/2" or 3" below that huge cover.

It is a horrible design. The pulley should be upsy down from how it is, which is with the largest pulley at the bottom.

So, I either deal with it, find a way to flip it over and fit a new cover, leave it and fit a new smaller cover ("only 7" instead of 8" wide), or get rid of the factory head and put a different one on it. Or move the whole thing to a new owner, I suppose. I could raise it up higher, but that makes the angle of sight to the work kinda bad, as well as putting your face in the line of thrown chips from the cutter.

I can't sell it for anything worth my labor, so that's out. Flipping the pulley is dubious due to the construction. And a new cover is "possible" but likely not very helpful, it would not make much change. That leaves putting a new head on it, preferably one with a quill, or "dealing with it".

Sounds expensive to put on a new head, so I suppose "dealing with it" is the plan for now. I can get some end mill adapters, but they will add lever arm to what is a fairly short spindle, probably leading to chatter, which is not a factor now.

it's a hell of a note......

[TGTool]

You just need a taller stand. It would be pretty visible with the table just about shoulder level.

Actually I'm with you on the annoyance of tools that are hard to use for one reason or another. Life's too short to accept constant frustration.

[J Tiers]

The taller stand is do-able, as is just stooping over to see under the "canopy". Problem is that then the view is at a "grazing" angle to the work, so if you were needing to see a layout outline, you can just forget about that and start counting handle turns...

Just taking off the pulley guard is the simplest way of improving the view, although it does risk putting grooves in your forehead.

Second is using end mill holders.

[Mcgyver]

A scraped surface isn't necessarily smooth but all the little plateaus over the surface are the same height withing a very small range, tenths to millionths.

Agreed. I also think the difference between the highs and lows is about a tenth. Its a function of depth of cut (a tenth or less when finishing by hand) and enough iterations to cover the surface. The proof is the needle of quality 10ths indicator barely flickering over the surface

Those who haven't done are often critical or suspect of claims to working to a tenth. In most machining that's probably justifiable, but scraping is different as the depth cut is limited to very amounts by the strength of the human body - with a given tool geometry there is a limit on how a cut you take. That's why scraping is work to tenths (and also why it takes so bloody long!)

This seems to be at odds with frosting for oil retention.

thats a notion so often repeated its accepted as fact. Not really sure myself, but every instance of its recommendation I've seen is only backed up by "experience" (we've always done it this way/I was told to do it this way) vs engineering or scientifically sound reasoning. When you ask for said sound reasoning and science you're usually criticized as an ivory tower type devote to pin head dancing counts from people who just get on with it and don't theorize. A worthy approach often, but also one that can perpetuate things that are little more than beliefs.

I do know from reading some tribologist stuff that they view the ideal bearing surface as absolutely flat so there is zero chance of asperities colliding (which is what wear is). The bearings float on a wedge of oil so there is no metal to metal contact. This is why a finely finished watchmakers lathe bearing (with no divots for oil retention) is still perfect after 100 years of use. I have never seen one with an irregular surface or seen anyone advocate for one. With the exception on ome of an oil distribution groove (ALL!! flat bearing should have that) both surfaces are dead smooth.

If these oil filled divots do in fact work as reservoirs and liquid leaps from them into service when needed....what replaces the oil leaving the divot? A vacuum? That scraping is such a great way to create well mated bearing surfaces, and once was the only way, its not unbelievable (since the exists anyway) someone proffered them as a virtue, that they're beneficial for oil retention

Like I say, I'm unsure on this topic because the argument does fly in the face of so much lore.....but I think there's a bunch of rational to make me at least question said traditional lore. Like the long held view of aging castings, just because a lot believe it isn't a good enough reason.

[dian]

consider the difference between hydrodynamic regime and whats going on with a surface plate or almost stationary ways. if the surface is "perfect" you get wringing, inter molecular forces and even self welding of compatible materials on a microscopical level like with gage blocks. and yes, this happens in vacuum also. such a surface will crape off the oil.

[J Tiers]

As far as the scraping for oil retention, there seems to be some evidence....

Looking to another medium, think of woodworkers. How is a "rubbed joint" made? In simple terms, you put liquid-like glue on the surface (slippery like a lube, until it sets), then rub back and forth. That both drives the glue into the tiny recesses, and drives it out of the joint with the goal of a thin but very good joint. If you do the rubbing too long, you get a weak joint, as the glue gets so thin that the surfaces touch and very little glue area is left. That is the same motions as a lathe carriage, or mill table.

The watch lathe bearing has an important difference from that. For one thing, it is rotating, and much of the oil that might be "squeezed out" is still in the area, not squeezed out and left several inches away, so the oil can, to an extent re-cycle. And the "oil wedge" can form due to the continuous rotation at a significant surface speed. While it is smooth, nothing is pressing it together with a heavy pressure. It is adjusted to the point where there is a very small, but definite "oil space" left. There is no significant pressure trying to reduce that space, since the working pressures on a watch lathe are tiny, and there is a supply of oil continually available during work from reservoirs, and due to capillary action. A lathe carriage or mill table has continual pressure on it, so the oil will be squeezed out until the surfaces touch if new oil is not supplied, plus the slow surface speed and intermittent movement do not allow much if any "oil wedge".

Larger lathes as a rule have pumped oil to the slides. Any industrial machine will have that, either a one-shot oiler, or a continual pump, such as a lathe where the carriage feed runs a pump feeding oil to the ways under pressure. They do not depend on intermittent oiling by the user. If you like experiments, just shut off that flow and see at what point the surfaces start to rub and gall.

This is "evidence", but of course not proof. But there is the point that in many cases, when examined, "what we have always done" proves to have sound reasons behind it. Very few things have developed as "folk rules" which have no basis in observable fact. (Changed conditions may allow changed rules, but the original rules developed to suit the conditions of the time)

My favorite "folk rule" is always having running water between your house and a graveyard...because ghosts cannot pass over running water...... That actually has sense behind it.

[mattthemuppet]

well, that's a bugger after all that work. You have restored a machine to its former glory (or better) and presumably gained a bunch of experience in the process, so that has value even if it's not a monetary one. I'd sell it on to someone who wants to use it and buy a replacement that you would want to use (Hardinge BBV? Similar size, chunky mill). As others have said, life is too short to get frustrated using tools you don't like using if you have the option of getting something else.

[nickel-city-fab]

I wonder if you could adapt a b-port head to it? Plenty of them on eBay. If you ever do decide to unload it, let me know. Figure some mill is better than no mill.

[Jim Stewart]

....................

Second is using end mill holders.

Yep. Why not?

-js

[J Tiers]

I'll probably just take the guard off the head for the moment. It was only horizontal when I bought it and I had a long-term plan to find a suitable head with a quill.. The machine was really not usable when bought, and I got it stupidly cheap. I had, and still have, no intention of using it as a horizontal mill unless forced to.

The plan changed when I picked up the V-head for $5, which meant I did not have to find or make a head. At $5, I could scrap the head and almost not lose money, but I am not going to.

I'll use it, possibly with end mill holders, until I find a head, or design one and make it. Most heads are totally out of scale for the machine, and the Rusnok, which is closer to right, is so ridiculously expensive as to effectively not exist. Plus, it almost does not exist anyway, they are not common.

[J Tiers]

Took the cover off. It's probably just enough better. Now it is not the pulleys, but the lower bearing housing that obstructs the view. However, one can see more of the cutter.

Of course now the pulleys are "right there" unprotected from bumping head or at least the hat brim on them (I wear a baseball cap in the shop to keep from bopping my head on things.... not much hair up there.)

[reggie_obe]

A possible visibility solution. Move the step pulley on the head to a countershaft and replace it with a pulley slightly smaller than the bearing housing with a matching pulley on the countershaft. Install a thin plastic or sheetmetal guard on the front of the head for safety.

Or, while the machine is still in freshly rebuilt condition, sell it to a Benchmaster aficionado and find a more suitable 3/4 sized vertical mill.

[J Tiers]

It is not the pulley at this point. It is the bearing housing, but that allows twice the visibility allowed by the pulley housing.

Sell it? Nobody would pay the price needed. After all, it may be complete with both spindles, and be freshly re-scraped, but it does not have the "original" vise! The collectors are already turning up their noses in disgust!

The long term (and fallback) plan was always to CNC the thing eventually, unless I find another machine first. Meanwhile I have a dedicated vertical mill, which I have used repeatedly. Without the excessively swollen pulley cover, it is tolerable.

The pulley thing was that if they had made it with the pulley upsy-down, the housing would have cleared the sight lines, even with ample belt change space. That cannot be done as a retrofit, the head will not allow it. And in any case, the housing and design "are as they are".

[J Tiers]

I used it earlier today to do some wood routing (!). Done to an outline on the wood, worked out OK. That was without the pulley cover.

I kept my nose and hat brim out of the pulley, and stayed between the lines, so I think it will work out for the moment, until I find a longer term solution. The lack of a quill is the thing I wanted to deal with longer term anyway, so I will probably either make or buy a new head for it.

It's still a good size, and I REALLY like having a bigger table with three t-slots. Maybe I can find a unit with one of the optional 36" tables, and swap parts around...... That would be the goods.

[J Tiers]

What I was "milling" was handles for the straightedge, so I can start with reconditioning (probably scraping) the bed of the Rivett. You know, the old make a part for a tool that is then used to fix something else.

Both (4 parts) now fit the straightedge, but are not yet finished with the hand-hold grooves.

It's plant season here, so less shop time. Besides the work here on the property, I need to go down and clean up plants for the annual plant sale that partly finances maintenance on 300 city-owned gardens in town. (Its a private charitable organization that does the work, partly financed by the sale, partly by contracts, and partly by donations). I'll head out in an hour or so. Got a little bit done in the shop, but lots more to be done.