Thread: Show us your Hercus

Hi Al

Here's the details of what I know on the issue.

I attended a talk given by one of Fred Hercus' sons years back. He stated that his dad had quite a background in the gearcutting business before building the 9". I believe gear cutting is still a major part of the Hercus buisness. He stated that his Dad purposely made every gear in the Hercus lathe have a pressure angle of 20degs because he believed that they were superior to 14.5degs.

Now that is not to say that it is impossible that your lathe has 14.5degs on the Bull wheel or elsewhere, or that this information is infalable.

I have read on a forum somewhere that southbend moved over to 20degs at some point in time. So another possibility is that the SB bull gear you have is actually 20degs.

I have a few change gears from a WW2 vintage southbend and they definately don't run as well as they should with the hercus gears.

Hi All well we have or should I say I have gone through every gear in my garage with the 16DP 14.5PA cutter and then took to my Toolmaker Al's this Morning and he did the same slow with Magnifying glass checked the gears on (SUPPOSEDLY ) original Hercus Back gears and all the gears matched the 16DP and 14.5PA

The most mystifying thing I found was a lack of supply of 20DP cutters in Australia as there is 8 in the set you would reckon that somebody would have NO WAY

I contacted a old Machinery salesman and talked in length and he tried to see if any of his friends had anything we could Borrow
(STILL NO REPLY ) I am getting a gear cutter from the States off eBay whether it good or bad we have to work out all the possible cutters we can find, I have read a million times Fred Hercus was not impressed in the 14.5 PA and improved and strengthed it to 20PA which up untill 3 weeks ago I was a confirmed 20DP20PA believer but after buying the ring gear from Mick Moyles they are not 20DP or 20PA but yet the cutter we have is exactly the right shape and pitch as the ring gears
so next week is set up the dividing head and start cutting and go with what we have now which is not 20/20
all the best Derek

To figure out the DP (diametral pitch) you take the number of teeth =N add 2 divide by gear OD. For example 56+2=58/3.22=18DP
Is this how you came up with 20dp for your gears derek? any pics of the back gear repairs yet, i'd like to see pics of the various stages. How much interference fit do u figure to sure for the gear rings and do u plan to heat them for installation? We used to do that with ring gears on flywheels for the starter in automotive just heated them with the oxy/acet and dropped it on to cool in place. ( my 2 trades tickets are automotive Machinist and also automotive Technician)
Well I guess I will be buying new cutters @ 14.5 deg........
al

Originally Posted by aljunk

To figure out the DP (diametral pitch) you take the number of teeth =N add 2 divide by gear OD. For example 56+2=58/3.22=18DP
Is this how you came up with 20dp for your gears derek? any pics of the back gear repairs yet, i'd like to see pics of the various stages. How much interference fit do u figure to sure for the gear rings and do u plan to heat them for installation? We used to do that with ring gears on flywheels for the starter in automotive just heated them with the oxy/acet and dropped it on to cool in place. ( my 2 trades tickets are automotive Machinist and also automotive Technician)
Well I guess I will be buying new cutters @ 14.5 deg........
al

Hi Al, the turned down back gear had a .05" interference fit we heated the ring on a barbeque gas ring and then just dropped it straight on the backgear

BUT we mad a jig up so aligning the gear onto the backgear assy was set flush so the gear could not go any further than the length we set the jig up to and this is only for the large gear
We have yet to do the small gear as we are waiting for the cutter same as the bullgear waiting for cutters
will take pics as soon as we get going properly as we just wanted to see if the gear distorted or buckled but put in lathe and runs true

all the best Derek

One way you could get to the bottom of this would be to have a close look at the rack. If it's 20deg PA the angle of the teath to the vertical will be 20degs. If it's 14.5PA it will be 14.5.

You'd probably need to pull the rack off to do this. Derek do you have a rack sitting around that you can measure?

Regarding cutters, one possibility is to make them yourself.

a pic of my old girl 1955 vintage s/n C5097 front bearing has about 3thou play the ways seem good except the bumps near head stock

Originally Posted by aljunk

Mine has the BS on the other rail too, wonder what the significance of this is?
Thanks for cluing me in Wannabe, I kinda figured it had to do with inspection or some kind of certification.

Hi. I think the "B" stands for basic and the "S" stands for shortbed model.
JohnH

Hi. If some one can measure the thickness of the top of the gear (not the width) compare this with a Southbend or a new chinese metic lathe, I think a 20 degree is smaller than a 14 degree, or it could be the other way round.
This sounds a bit muddled, but I read it in Model Engineer, or something, so a rack or gear with similar DP and tooth number could point you in right direction.
John H

I have both a long and a short bed machine and both have the BS on them. The model/serial numbers are different in that the longbed one is an ARL where the other is an AR.
As for the gear angle, I convinced they are 14.5 not 20 as the ones I cut this week were 20deg and looks very different than the originals.

In that case I apologize for giving you bad information Al

No problemo Blackfrancis, it seemed to be the general consensus on here.

al

Well I have most of the pieces painted and reassembled!!! Just hunting for a few adds n ends now, like some felt material to put in the gearbox oil slots etc.
It's a lot more work that one might think to strip one of these babies and do a full restore, new headstock bearings etc.

al

Have fun with your lathe but I fail to see why the control switch is mounted there looks suicidal to me quick way to slash a wrist or worse, off to the side or in front is much safer. With yours you have several chances a session of potential harm.Mine is mounted outside the lathe on the left. Tell me how you find the switch using steel or other materials larger than the chuck.

Cheers mate.

Regards Peter.

Hi Peter, my 1954 factory switch was on the opposite side of the chuck so you had to lean over the chuck to turn it off
at least I see John has a knee KILL switch
A lot of the early 40's and 50's lathes they put the switch in what we now call dangerous spots back in those days no loose clothing tight fitting overalls to the wrist plus as they were originally a PRECISION lathe no mass of flaming swarf would be ever allowed to build up plus the machining was small parts
John's switch is mounted on the same bracket probably as mine was but flattened out to mount that monster switch and as John has plans like we all do his picture is of the lathe when he bought it
I have seen lathes that do not have anyswitch bar lean over and turn off at the powerpoint
My switch sat in the same spot when I rebuilt the first time but never wired it up I eventually got a SouthBend Switch mount ground the back flat and is now mounted on the Headstock were the Hercus sticker use to be

And as I know abit by emailing John who is chasing parts, for the price and were he bought it would astound a few owners and one day it will get there mine is 17 months and still modifying

all the best Derek