Single vs Double Wall Aprons

Hello all; I am a new-join and glad to finally be on-board. I have been a long-time reader of various topics -- mainly because Google provides links to P.M. for many questions I often post. I am far from a machinist, but, rather someone who fixes everything - pretty much everything I own; including cars, trucks, engines, transmissions, boats, motorcycles, ATV's, mowers - you get the picture.

Anyway - I am in the market for my first metal lathe. I was considering a Hendey tie bar listed locally, when I stumbled upon Patrick Black's 14x6 rehab thread. I read it, and re-read it four or five times. It's difficult to admit and even harder to explain - but now I am committed to owning a Hendey tie bar lathe. The deal fell through on the original Hendey but now another one has popped up, even closer to home. I took a look at it over the weekend and I was impressed. It comes with a good amount of tooling, including a set of collets. Although it's only a 12" model, it is a few years older and thus has the single wall apron.

The auto-feed appears to function properly in forward and reverse. The owner informed me that when feeding manually, however, there is a gap - where he thinks there might be broken teeth on one of the gears. I am not even sure that is the issue, but it got me to thinking about the lack of support with the single wall apron...and whether that could lead to a problem like this. So my question - to those who may know - is there any practical difference between the two designs of apron? If you were using the lathe as intended, and not taking particularly heavy cuts - would I even notice the absence of the second apron wall?

Teufelsschlussel:

Intriguing handle you have- Devil's Key. Welcome to our 'board. I am sure Hendeyman and other 'old heads' can better respo nd to our post. However, single wall vs double wall apron is a common question. Single wall aprons were fine for their times. The era the single wall apron was designed in was an era when forged carbon steel cutting tools were in use. Add the fact that the lathes were line shaft driven, often through multiple belts with varying loads on the line shafts from other machine tools. Available power, possible belt slippage and lighter tool loading all added up to conditions where a single wall apron was not going to be overloaded.

With the move to high speed steel tools and better drives for the lathes (including individual motors, albeit thru flat belting), the double walled apron came into being.

There is nothing 'wrong' with a single walled apron. However, like any other machinery that is 100 or more years old and having an unknown past, wear and damage are expectable. Apron gears running on steel shaft journals are bound to have bores worn oversized changing how gear teeth mesh. But, on a lot of old machinery, as sloppy as parts may appear, they often 'wear into' each other and the machinery continues to operate. The problem I've found with this sort of thing is if I start to make a repair or replacement for one or two badly worn parts, when the running fits and similar are 'tightened up', it often throws off how the next few parts in the mechanism work, and reboring/rebushing and similar going a bit further into things often follows.

As for the issue with the manual feed of the carriage, I'd suggest seeing if the carriage feeds under power vs not being able to feed it manually. The apron gearing is not high speed gearing, so repairs to it can be done with relatively simple means. Many of us have repaired broken gear teeth by building up the 'root' of the tooth with brazing. If room permits, tapping in a few steel screws to act as 'dowels' to give a positive attachment for the brazing is something commonly done. The steel screws wind up encased in the brazed buildup. The brazed build up is then re-shaped to the tooth profile by any means handy- filing and 'rolling in' a mating gear to check tooth mesh being the most basic method. The beauty of a brazed repair is that the brazed metal can 'cold flow' or be cold worked by the meshing and contact of the mating gear teeth. This will bring the brazed teeth to final profile, as well as work-hardening and burnishing the surfaces of the brazed teeth.

From the sounds of it, there is damage to a gear between the carriage feed handwheel and the rest of the gear train which is used in either power or manual feed modes. I'd say a brazed repair of the damaged teeth will work fine.

The big question as to 'heavy cuts' is what class of work did you have in mind for your lathe ? A 12" Hendey lathe as you ask about is not a lathe with high enough spindle speeds or rigidity (at this point of its life) to really be running carbide cutting tools. If you limit your work to using high speed steel tools, I am sure you will find the lathe to be more than adequate for anything you need to do with it. Even my old South Bend heavy 10" lathe, with flat belt drive, can take a surprisingly heavy cut with a HSS tool bit that I ground freehand. Cuts on the order of 0.100" - 0.125" off a piece of 1 1/2" diameter steel without running in back gears are something routine. I have three lathes in my shop: a 13" LeBlond Roundhead Regal, the 10" SOuthbend Heavy 10", and a lighter Southbend 10" which was given to me. I haven;t run any jobs in the little Southbend in ages. I do not know what you envision doing with the Hendey lathe, but I am sure that it will be up for most, if not all, the jobs you may run on it. Unless you see yourself doing something pushing the envelope of the lathe in terms of capacity and type of work (such as a rough forging or hard-scaled casting of large size), I would not give the apron design a second thought once you go thru the apron and put things to rights.

I have a 1909 16" Hendey with the single wall apron. The lathe as a whole has quite a bit of wear, yet everything "worked" when I first got it (currently down for repairs).

Like Joe Michaels, my take on the single wall apron is that it works fine, it just isn't as good of a design as the later double wall. On mine, the feed worms and worm gears took most of the abuse likely just from lack of maintenance. They are very sloppy with sharply worn teeth and will need to be replaced. In addition to that, most of the shafts running through the apron have worn in an hour-glass shape since the shafts are supported in one place and can see forces torquing the far ends up and down. This isn't nearly as much an issue on a double wall where both sides of the shafts are supported. These are not difficult to repair however, as the apron can have new bushings installed and new shafts can be easily machined. Given how old these old single wall aprons are, IMO if you make repairs and take care of your machine, they should last at least another 50 years.

If you have the choice, by all means get a Hendey with the newer double wall, but my experience has been that machine tool markets are not as predictable as they once were. I'd rather buy a so-so Hendey and level-up to a better one later, than hold out for something better and never find it.

One the bright side, even though there are no parts available for the old Hendeys, the original blue-prints are! (paging Hendeyman)

I really like my Hendeys but are of newer design . Gear heads built in the 40s. If your in Michigan there is a nice monarch in lambertville . Lot newer design. Seems decent price too

Thanks for all of that Joe Michaels, great information in your reply. I have seen gear repairs documented here on P.M.; in fact Patrick Black completed one such repair - by brazing as I recall - on his Hendey. I think that would be within my wheelhouse, although I've never done such a thing before. It is good to know that broken/chipped gear teeth are not a deal breaker. I was very impressed with this Hendey I went to see last weekend. It is a 1911 12x5 tie bar complete with all tooling, although I am not sure about the taper attachment. For it's age, the lathe seemed to be in exceptionally good shape. As far as I could tell, it only had two coats of paint - both black. The lathe seemed pretty smooth/tight -- but I have nothing to compare it to so that's not saying much.

One thing that you brought up was the use of carbide tooling. I expect to use carbide on one of my very first projects, maybe ceramic. I need to turn down a transmission sleeve to reduce it's diameter by 4mm in order to accept a new bearing. I am told it is made of a quality, hardened steel and I suspect from what I have read that HSS isn't going to touch it. I'm not even sure carbide would work thus I assume I may need a ceramic insert. I am in no hurry and thus I have no need to take a large cut, although I am made to believe that ceramic performs better when speeds are increased and you get into it a bit.

Mr. Naelge; you, sir, hit the nail on the head. The original lathe I was looking at would have been just about perfect in my mind - a 14x6 Hendey tie bar including a bunch of tooling for only $500! Since the deal fell through I have been searching all over and as you said, I may have to take what's given and look towards upgrading later. There is a really nice 14x8 Hendey listed by another PM member as we speak. I would be on my way to NY right now if space wasn't a concern for me in my workshop.

Mr. Marquette; I appreciate the tip. I found the lathe you're referring to. It is a beast! That's a lot more lathe than I am interested in starting out with. It would also hurt that no tooling goes with it. I have my mind made up on a Hendey, but I'm sure I could change it under the right circumstances. Thanks for the heads up.

I have a 14x6 single wall - so far mine is looking good but I've stripped it completely down to clean / paint. The apron seems in good shape etc. The biggest thing I can think of that might affect your decision is your 1911 probably has "Plain" bearings...meaning they aren't ball bearing or roller bearings. That pretty much limits top speed to 400 - 500 rpm on the spindle. My understanding is for carbide you would want 1000+ rpm. It depends on the diameter of the workpiece as rpm by itself isn't the measurement you need...its a variation of feet or inches per second I think (I'm saying it wrong but hopefully you understand (fwiw I'm just a hobbyist myself))....essentially a large diameter part turned at 400rpm might get you into carbide distance per second range versus a small diameter wouldn't.....I hope this helps. I'm having a blast learning on my Hendey and I love it but I also forsee a time a couple years down the road where I get a nice monarch lathe too.

Looks like I might have to take that particular project somewhere then - I didn't realize the old Hendey's didn't have enough top end to handle that sort of thing. I was hoping to take some nice, easy cuts and - get there eventually. Thanks for that information.

Teufelsschlussel:

I am am glad you appreciated my reply. Your mention of needing to machine a hardened steel transmission sleeve brings a recent job I did to mind. I was asked to machine a spring retainer ring groove in a splined shaft. The shaft is used in the final drive of later series BMW motorcycles. I knew the shaft would be hardened. I set it up in a 4 jaw chuck, indicated it so it ran dead true, and ground a carbide form tool to cut the groove. The shaft was supported in the 4 jaw chuck and also by the tailstock center. I attempted to plunge in with the form tool for the groove. About all that happened is the toolbit 'sang' on the splines. While I do not own a hardness tester, I am inclined to think the hardness was somewhere up around Rockwell 55-60 C.

Time for 'plan B'. I had some very small, fine grinding wheels from the local industrial surplus store. I mounted one of these wheels on my DuMore toolpost grinder, and dressed it to the profile of the groove. I then replaced the toolpost on the lathe with the toolpost grinder and proceeded to grind in the groove. I had 50 cents tied in each of the small grinding wheels, and simply held the dressing diamond in a chuck in the tailstock. I swung the compound of the lathe with the grinder on it to the required angles and dressed the wheel to the required profile. It was like night and day. The little toolpost grinder made short work of putting in the groove.

Over the years, I've learned to treat any automotive axle splines, transmission or similar shafting or sleeves as being too hard for carbide to touch. In most cases, I am salvaging the steel from those parts to make other parts or tooling from. I full anneal automotive or similar shafts or other similar parts before I start any machining. You are wanting to keep the hardness in the part, so the job falls into the same category as the job I've described.

My other concern when these sorts of jobs come my way is: 'depth of hardness'. Some parts are not 'through hardened', but are 'surface hardened' by processes such as carburizing or nitriding. These processes change the metallurgy in a surface layer of the part being heat treated. This change in metallurgy allows that surface layer to 'take hardness' while the inner core cannot take hardness. After appropriate quenching and tempering, the surface layer or 'case' is hardened to meet specifications while the inner core remains relatively soft. This combination produces excellent wear resistance on the outer surfaces and good shock resistance through the entire part. The 'case depth' varies with the design of the parts. Typically, case depth is figured with some allowance for finish grinding to final dimensions. Case depth is a function of how long the part is allowed to 'soak' (remain in a furnace or oven at a temperature above its transformation temperature). As a rule of thumb, the case depth usually is figured at about 0.001" of case depth per hour in the furnace, with the part having been exposed to an atmosphere or contact with chemical compounds that will be absorbed into the steel. Carbon rich compounds (carburizing) or ammonia gas (nitriding), or potassium cyanide are the common compounds used to alter the metallurgy of the surface layer in parts to be 'surface hardened'.

When these sorts of jobs land in my lap, I approach them with caution as I do not know the 'case depth' vs 'through hardened'. Not owning any hardness testing equipment, I will sometimes do a little 'destructive testing' if the job allows it. This can be slicing an extra piece thru with an abrasive cutoff wheel and using files and a center punch to do a 'poor man's hardness traverse'. Another test is to cut partway thru the part with the abrasive wheel, then hold the part in a solid and heavy vise so that the cut is about even with the jaws. I then hit the projecting portion of the part with a 3 lb blacksmith hammer and see what happens. If the part breaks off and flies, I then do that poor man's hardness traverse as well as examining the fracture. If the part takes a few more blows and shows signs of some ductility, then I know I am into something surface hardened. My methods are crude, but when these sorts of jobs find me, I tell the customer up front about my concerns.

Not to throw a bucket of ice water on your plans, but sometimes not even carbide or ceramic cutting tools will touch some of the hardened steels. I use the old machinist's file test on anything I suspect may be hardened. If the file truly 'skates' and 'sings' as it goes across a corner or edge of a suspect part, the answer is that the part is 'file hard'. Usually, file hard is too hard for cemented carbide tools to touch. I've used carbide die drills and solid carbide reamers on jobs in hardened parts, but those items were pricey and not meant for hogging off large amounts of metal.

Great story, Joe. Improvise, adapt, and overcome, as we often said in the military, right? I have read with interest other accounts of grinding such hard metals rather than turning to obtain the desired results. In this case, I have information that the sleeve in question can be turned. The person who has done it posts on another forum and he advises that he uses ceramic inserts. I never bothered to ask what kind of lathe he uses but I might assume it is a good deal larger, or more powerful than the antique Hendeys I've become rather fixated on lately.

I enjoy your writing style, Joe. With the amount of information you have to pass on, you might consider writing a book! I think I would buy it. Truth be told, a lot of the information that you and others on this forum posses is dying. Much of your "common knowledge" is now decidedly uncommon. There are still a lot of handy people out there, like me perhaps, who do a lot of things for themselves; but as you very well know - the skilled trades, like tool & die and machinists - have been dying a slow death.

I grew up here in the rust belt, in the Lansing area - which was, of course, a big GM town. If you didn't work for GM, you worked for state government, or the large university next-door. As GM began to move production overseas (and out of state) all kinds of related businesses closed their doors as well. That, of course, is why so many of our cities - Flint, Lansing, Saginaw, Pontiac, Detroit, Muskegon, etc. - have struggled for the past forty years. I think we lost a lot of skilled workers during the 80's and 90's but more importantly we lost a quality of life that is yet to return.

Let me be clear - my response earlier wasn't a lack of power or rigidity - its a lack of speed. The hendey can provide incredible torque via the back gears...take off huge depth of cuts. The problem becomes when you need high rpm as the really old ones the spindle runs on a bronze (or is it brass?) surface with an oil film. There is no roller bearings to reduce wear. If your part has sufficent diameter the Hendey can handle carbide just fine ...it goes back to the calculation I stated...assume a top spindle rotation of 500 RPM. Little Machine SHop has an online chart or there is info in the Engineers Notebook....You simply need to know what rough speed is called for for carbide or ceramic, the Circumference or your part and then you can solve for the recommended rpm you need. Cutting Speeds - LittleMachineShop.com .. If you have 500 RPM and a 1" Diameter part : (circumfrence = 2PiR) 2PIx.5 gives me 3.1415 inches per rotation....so 3.1415 x 500 would yield 1,570 inches per minute. a 2" diameter shaft would be 6.28 circumfrence or 3,125 inches per minute (all the real machinist please feel free to educate me if I've gone off the rails). ...My point is 500RPM is slow if you are turning a very thin part. The second you turn a larger diameter part the rpm becomes less of a factor and power(which the hendey has) becomes more of a factor because it can turn the heavier parts. I hope this helps/makes sense.

Riftware; I do understand - thank you. I need to take a look at a couple of cutting geometries; select an insert; obtain the numbers; and plug them into the formula. I know from talking to a couple of local machinists that the hardness of this part was a concern for them. Thus their tooling, machine capabilities, etc. One suggested that he might grind it - as Joe related above. The other didn't even want to try to turn it - more I think because he is set up as an engine shop and not a machine shop, per se. Anyway, what he would charge to reduce the diameter of my sleeve made me start looking at buying my own tool (machine) to do it myself - as I often do with various things. May not pay for itself the first time you use it, but it certainly will pay for itself down the road.

One other possibility would be to get a tool-post grinder to go with your lathe. High RPM isn't necessary and with the right abrasive wheel you can cut about anything. Biggest concern will be to keep you ways covered while you grind as the abrasive dust will accelerate wear. Flood coolant will help, but you'll of course need to contain it, but investing in that will also help with your general cutting needs.

After my 12-30 gear head wasn’t enough size I found a 18-54 tie bar . Well after I looked at there is no clutch to slowly start spinning work up to speed (which could have been over come with a soft start VFD.
Plain bearings, single wall apron and the belt drive. I started looking for a gear head and replaced it before I got it running . Gained all that and an oil pan which yours might have. Didn’t worry to much About the top end only spin mine about 277 still have two more speeds to go and never use em. Also moved up to a 24” which was plenty . I have a lot more use for one than you might but glad I made the decision. From my experience is why I brought up the other. Be nice to see someone put obe of the really old ones to work. Keeps it from going to worse fates .

Cone Head Hendey speeds - thanks to hendeyman

This I think goes with the double wall apron period - before that may have been a bit less

https://www.practicalmachinist.com/...-head-spindle-speeds-191988/?highlight=speeds

have fun

Before any of them (with the plain tapered journal bearings) are expected to be metal removers they have to be free of the common ailment we refer to as hendeyitus - where the front spindle journal tends to bind in its bearing

johnoder said:

Cone Head Hendey speeds - thanks to hendeyman

This I think goes with the double wall apron period - before that may have been a bit less

https://www.practicalmachinist.com/...-head-spindle-speeds-191988/?highlight=speeds

have fun

Before any of them (with the plain tapered journal bearings) are expected to be metal removers they have to be free of the common ailment we refer to as hendeyitus - where the front spindle journal tends to bind in its bearing

Click to expand...

According to the "Lord of all things Hendey", the speeds listed are the same for 1899 to 1904 [pre tiebar] machines too!

M.B. Naegle said:

One other possibility would be to get a tool-post grinder to go with your lathe. High RPM isn't necessary and with the right abrasive wheel you can cut anything

Click to expand...

Yessir; I see about as many tool post grinders as Hendey lathes around here; but - if I end up with a lathe (of some sort) I will definitely keep my eye open for one.

Mr. Marquette; I see what you mean about those Monarch lathes. The big one would be very capable although the older cone-head would be more my size/speed. The price is right so I'm going to keep them in mind. Another forum member invited me over to check out his lathes (he has two 14x60 Hendeys) so I'll take him up on the offer in the not-too-distant future.

Lucky you. You get to go see and maybe a little test drive of the same model Hendey as you are looking at! Talk about a golden opportunity to learn what made them special!

dundeeshopnut said:

Lucky you. You get to go see and maybe a little test drive of the same model Hendey as you are looking at! Talk about a golden opportunity to learn what made them special!

Click to expand...

It's better than that, dundeeshopnut; this gentleman has offered to teach me some things as well! I'm looking forward to it.

t.r.