Brass cap screws I made for Juan's planes

[george wilson]

These were made for Juan's planes. They look nice in these pictures my wife took,so I thought I'd post them with a little info on how they were made.

Right now,I can't recall actually seeing these style screws on an antique plane,but they have the right look for 19th.C. designs. Maybe I invented them? Senior designer moment?

They were made from 7/8" bar 360 alloy brass. All these years I've been making their curved parts by freehand turning,but since these needed to be pretty much identical,and were needed quickly,I finally got around to making a form cutter.

The cutter was made from a 3/8" square HSS lathe tool by freehand grinding on the edge of a grinding belt,and cleaned up a bit by use of a carbide cylindrical rotary file in the drill press. Then,they were honed with an India slip stone to finally smooth the cutter up so it would produce as clean a surface as possible to avoid excessive sanding. Highly finished surfaces on metal I've never gotten with a form tool. They are also prone to chattering unless you have a good rigid lathe and a rigid mounting for the cutter. Brass is easier than steel to form cut,though.

Normally I'd just have used annealed 1095 steel,much easier to deal with since it can be sawn and filed,but I had none on hand. Over the years I've made dozens of these special form cutters,and most often they are for a single use. 1095 holds up just fine for turning 01,just use slower speeds. After all,this was pretty much what they had for hundreds of years before HSS came along,then carbide. They started making carbide by using the breeches of old 14"and larger naval guns buried end up in concrete to make the high pressures and temperatures needed to make carbide. Not sure if sintering is the correct word,and I'm getting tired,so am losing memory!!

I also made the knurl by rotating a disc of 01 horizontally against a rotating thread tap held in the lathe chuck. I posted how these knurls are made in an earlier posting here a few years ago. It can be searched. Use George Wilson,knurls I made,and it will likely show the posting with pictures.

After careful sanding with 600 wet or dry,these were minimally buffed so as to not damage the details. The knurls were not buffed at all,nor were the 3/8" 16 thd. shafts.

The balls were freehand turned.

[Klaus Kretschmar]

I wished to have only a small part of that talent in metal work!!!

In awe
Klaus

[Trevor Walsh]

George, or the workholding on those, do you turn down and thread, part off the bar for the head material then reverse and chuck in a collet or threaded chuck, and form, knurl and finish?

[george wilson]

I use a collet chuck in my HLVH. There is no substitute for speed(there is a substitute,really,just not as handy)!! First,I chuck the 7/8" rod in a 7/8" collet and turn the shafts down to size,using a 6" steel rule to set their length,then thread them while they are still in the collet. The thread diameter must be miked,but once the crossfeed setting is noted,the lathe will very accurately repeat on the required diameter.
For more precise length settings,I have other means,like the digital read out on the lathe,which I hardly ever use for decorative parts like these.I can do a 64"th. consistency with just the rule. Then,I turn down a step in the 7/8" rod to eliminate most of the extra mass,but leave 5/32" full diameter where the knurl is to be. I round the edges of the knurled (to be) area to fit the contour of the knurl. If the surface doesn't fit the contour of the knurl,a poor knurl will result as the metal can only be mashed so much before it starts to flake apart,especially cold rolled brass,which is already rolled pretty much near its limit of malleability. Then,I knurl the contoured area. I just used a file to contour the edge,though grinding a cutter would have been quicker if I were making a large number of these screws. I held the knurl in its holder against the contour,pressing it against the revolving brass,and filed off the faint marks till a decent fit was had.

The brass is then cut off,leaving enough material to make the stacked up head. When all these screws have been processed thus,I put in a 3/8" collet and hold the screws by the screw threads to finish their contours. This is where a collet(or something similar,like a slit tube held in a 3 jaw chuck) is indispensable. It won't damage the tops of the threads as it provides a 100% even grip on them. When I didn't have a collet lathe,I'd have to use a slit tube of the right diameter as mentioned. Not quite as concentric,but to the eye they looked fine,and these are not high speed turbine parts. With the Hardinge collets,I get .0001" concentricity. With the 3 jaw,more like .003". At this point,the screws are sticking out head first,with a step down turned into them about 5/8" in diameter(I'd have to go look at my drawing),to minimize the cutting forces which the tips of the threads have to support without rotating and galling in the collet. The form tool is applied,and the contour nicely cut straight down into the heads,going a little below the knurls,leaving a little groove just inside the knurl line. A 1/8"X 1/8" stalk of brass is left sticking up to make the round ball. A crude tool rest is put onto the tool block-just a 1/2" square piece of bar stock sticking out sideways from the tool post. I rest a freehand turning tool on this and turn the ball. I have made a set of small turning tools with ball shapes milled into their ends. They are sharpened by grinding their top surfaces,and have lasted many years. They are 1095 steel.

The lathe is covered to protect it,and 320,then 600 grit paper is applied till all the turning marks are gone. Lastly,the heads are given a light buff without touching the knurls,which need to be left crisp.

Oh,yes,the end of the threaded shanks were turned just below the minor diameter of the threads. If not,any bulging of the threads AT ALL,from screwing against the plane iron,would make it impossible to unscrew the cap screws without possible damage to the female threads in the cap.

My aim during many of these processes is to avoid turning the lathe on and off as much as possible. Those old relays are large and very expensive,and are from 1964. There is a whole cabinet full of them!! I can often pop a part out of the collet and pull the next length out with my Leatherman without stopping the lathe. These parts were to heavy for this,though.

[ray hampton]

these are remarkable work

[george wilson]

Thank you,Ray. They are not very complicated parts. All design with some reasonably accurate work.

[ray hampton]

I think that you cut screw slots but am not sure, please how you cut screw slots, straight slots only

[george wilson]

I cut straight screw slots only,because all others are ugly and not fit to be seen on 18th. or 19th.C. style work!! :) Actually,I have seen a few 18th.C. flintlocks with neat,square holes punched into their flintlock hammer screws,with a screwdriver to mate with them,but they just seem so bizarre,and look like modern deck screws with square drive heads.

Generally I saw them with a hack saw and file them smooth with needle files for normal size screw heads,say,about 1/2" diameter. You don't want to see the chattery looking bottoms in the grooves that wavy hacksaw teeth leave,and they must be needle filed away. If I want real THIN slots,such as used on fine guns or instruments,I saw them with a jeweler's saw.

If I'm REAL serious,and want absolute perfection,or have a lot of screws to slit,I can saw them in the milling machine with thin slitting saws all the way down to .010",but the ones I can cut by hand are perfectly nice,too. Generally,I seldom use a milling machine because it is a bother to set it up.

Starrett made special hacksaw blades with no set in their teeth,and in different thicknesses for cutting neat screw slots. Years ago,some were gifted to the museum,but the gunsmith shop got there first!! I know they made good use of them.

I should get off my duff and order a set for myself if they are still available. Starrett probably wants $50.00 per blade,though,so I'll just have to keep on struggling along somehow (tears). Or,I could simply make some out of 1/2" wide spring steel shim stock.

The thin slot in my bronze drill's screw was hand cut and filed with a very thin file. Another bad picture.

[ray hampton]

I be afraid to use a needle file that thin because if I sneeze , my hand would break the file, do they drop forge the other types of screw head clutch, torx, Philip ?

[george wilson]

They forge them usually by drilling a round hole first,then punching the shape in. The blacksmiths would do the same thing for an odd shaped hole,like on the flintlock gun I mentioned.

[Ryan Mooney]

Thanks again for the detailed explanations. It makes these projects so much more interesting to read about.

[Juan Hovey]

George made these screws for my plane, making me the beneficiary of his talent and discipline. I send him many thanks.

Here are some pix of the plane shaving what I believe to be Cuban mahogany, lacewood, and some very old, very hard quarter-sawn oak, all of it picked up recently at a garage sale, plus a ton of black walnut and heaven knows what else.244952244953244954

[george wilson]

Juan,unless that is very light colored Cuban mahogany,I'm afraid it is Honduras. Is it too heavy to float? My real Cuban feels like it's nearly as heavy as ebony,is a much darker brown color(though I HAVE seen lighter colored examples from genuine Cuban mahogany trees blown down in Florida),and extremely hard,and I mean extremely.

That is lacewood. The oak is too out of focus to tell.

Did you get any orders at the show? I'm sure you will have many more planes to show next time. I will say that you definitely have more energy than I do!! Hopefully this vitamin D2 12 week regimen will help my energy level.Doctor says I'm critically low on it.

[Mel Fulks]

I worked for a guy many years ago who had a piece of an old piano case that was Cuban mahogany veneered with Brazillian rosewood .Used both for patches . I used to wonder what could have happened to that piano?

[george wilson]

Here's a peculiar story: The millwork shop in the museum made the best doors for historic buildings from mahogany. They made a mahogany door for one of the prominent buildings,then sent it to the paint shop to have it PAINTED and GRAINED to look like mahogany!! Why? There was a record that a mahogany grained door had been made in the 18th.C. for that building. It would have been made of a more common wood and mahogany grained back then,but to make the doors last longer,the millwork shop made them of mahogany though every one of them would be painted red,or white,or whatever.