O.T.:For plane makers; how to make knurls

[george wilson]

There is a fairly simple way of making the convex,"threaded",or rope knurls used in the old days for fine work. Objects such as microscopes,telescopes,the cap screws of planes,and a myriad of other high class work employed such knurls. They used to be available in a huge number of patterns. Yet,today,they are hardly ever seen. My friend,the emminent miniature maker,Rivett 608,is the only person I know who has a reasonable collection of old knurls. He is afraid of damaging them,so refuses to use them for the most part. He paid dearly for some of them,too.

These pictures were taken on my Hardinge HLVH metal lathe. It is one of the finest lathes ever made for smaller work,being 11" x 20". It is very good for this type work since it uses collets as well as chucks. Usinc collets ensures concentricity,but also keeps dangerous chuck jaws from flying around close to your fingers. You can also get closer to the work without large chucks in the way. However,a conventional metal lathe is perfectly usable. I used to use a 10" x 24" Jet lathe without collets.

The first pic.on the left is a blank knurl being made from 3/4" 01 drill rod. 01 is less risky than W1,which is much more prone to crack You MUST make the contour very close to the same radius as the tap you are using,or you may quickly find yourself getting a messy job when you try to thread the knurl.

If you are making a concave knurl,and for some reason want to run it against a convex blank,it is even more necessary to make the 2 surfaces THE SAME,or your knurl will not come out.The drill rod will not take much deformation into a knurled surface via pressure rolling before it work hardens,and can damage the knurl you are using as the "mother" knurl.

IMPORTANT: I like to use a 4 flute tap if possible. The flutes are smaller,and the cutters tend to engage at the top of the knurl just as the flute is leaving the cut at the bottom of the knurl. The knurl must be FREE to revolve,or it may stall out while you are cutting it,and make a flat spot,ruining the knurl.

The 2nd. picture shows the knurl holder,which is also made of drill rod,pressing the knurl blank against the revolving tap. Note that the outboard end of the tap is supported in a little female center to keep it from bending and breaking under the cutting pressure. In pic.5,you see the ball bearing dead center I like to use. This center isn't cheap. It is a Royal brand,with roller bearings inside to allow frictionless rotation of the male center. The 2 tubular objects are female centers I made from drill rod. They slip SNUGLY over the male center so the tap can be inserted into them.

The last picture is the knurl holder. It is drill rod. The axle screw is threaded a short distance on 1 end. On the other end is a screw slot. The center area of the axle is left smooth for the knurl to run on. OIL everything when cutting knurls,lest they stall out during being cut.

Another thing: Keep the knurl holder,knurl,and axle free of the tiny,crumbly little chips you will make. MAKE THE WIDTH OF THE KNURL a running,but good fit in the knurl holder,so the tiny chips can't get in and stall the knurl wheel.

The shank of the knurl holder is round. It fits into a 1/2" collet. The reasons it is round are 2: First,you can TILT the holder up to roughly 20º when cutting the knurl,to the RIGHT to increase the angle of the rope knurl. If you cut the knurl with the wheel exactly parallel to the tap,you will get the same angle of thread that is present on the tap. Tilting the knurl holder a bit to the left,you can make the knurl have vertical threads. You can't tilt much to the left,or bad things start to happen. SECOND reason the knurl has a round shank; I can put the knurl in my milling machine,and run the knurl back and forth across an annealed plate of tool steel. This produces a plate like in pic.#4. Repeating waves touching each other. I made this for pressing this design into the back sides of our jewelry either with a rolling mill,or in my 50 ton press I made with a 50 ton bottle jack. All our jewelry has patterned metal on their backs. This makes the jewelry more interesting,and makes the castings look better.

In the BAD pictures of several knurls,on the left end,you can just make out the "wave" knurl. In the picture that shows the wave knurl in front of its "mother" knurl,you see how the knurl was made. First,I made a punch of a single wave. Then,I made a knurl blank with a groove that just fit the height of the wave. Then,I punched the wave all around the mother knurl. It is important that you adjust the diameter of the knurl so that the waves meet perfectly at the last one you punch. After hardening and drawing to a dark brown color,I ran the mother knurl against the narrow final knurl,which also fit into the groove. Thus producing the knurl I wanted.

SOMETIMES I TURN the lathe BY HAND when making a figural pattern like this,to see how it mates up with the mother knurl.

In picture 3 is a BAD picture of the side of a knurl. I always stamp the type of metal on the knurl,and my initals. Hence the 01,and GW which you can make out barely.

As mentioned,I harden the knurls. It is best to STOMP the hole in the knurl tightly with FINE steel wool. Use a flat nose punch. Filling the holes of ANYTHING you are hardening keeps the holes from producing a crack and ruining a lot of work. You NEED TO REMEMBER THIS WRINKLE.

I believe I hardened these knurls in water. You can get by with water for SMALL objects. The water must not be cold. Room temp. is fine. They were hardened at a dark brown color,BUT,the water's minerals turned the knurls bluish. I think it's the iron that does it.

I hope that this information will be useful to those of you who have a metal lathe,and are making cap screws for planes,or for whatever other reason.

[Jonathan McCullough]

Nice technique. I've heard that some people make worm gears that way. Also, not often you see a hand-scraped surface any more. Pardon my lack of understanding since I've never knurled anything, but how do these knurlers behave during operation? If, during use the knurler makes contact with the work, and the work rotates one cycle, and the knurler has a diameter that is different than the diameter of the work, is there not the chance (indeed the inevitability) that the individual ridges laid down on the first cycle of rotation not therefore correspond with the ridges laid down during the second rotation, and you could get sort of a hash instead of an even knurl?

What about the wave pattern knurl? Is that for just the one diameter?

[David Weaver]

Ditto on the question about the differing diameters.

George - second question, i think you have mentioned that you've filed some of the knurls also.

I don't have a metal lathe and was thinking I might try filing them by dividing a knob into quadrants and then basically halving each quadrant, halving that, etc with light filing, to get the spacing and then work filing the knurling to full depth once the spacing was set.

It would take a LONG time to do that, but nothing gets done quickly by hand on an infill plane, anyway.

[george wilson]

The rope knurls generally have a small enough pattern to come out fine at any diameter. The wave pattern,you must be ore careful of. Run the lathe around by hand,and adjust the diameter till it comes out all around in registration. The only use I really have made for this knurl is to make the flat plate for printing waves onto silver,or brass in model making for jewelry.

You would have to experiment with diameters increasing in circumference by 1 wave at a time. Thus you could do many different diameters as long as the pattern meshes properly.

I hand scraped and flaked my HLVH when I rebuilt it. On surfaces like you see here(the top of the compound) it is just decorative. This is a 1964 lathe,and the exposed surfaces of the carriage and compound were marked with many little dents from years of use. I removed them by putting on this surface. The carriage of the HLVH is not like other lathes. You can't just take the top of it off and re-grind it. It is a large "L" shaped casting. I just did this in situ. Others have done similar things.

[george wilson]

I did file the large cap screw on my curved sided infill plane in the FAQ section. You can buy CHECKERING files from Brownell's Gunsmith Supply.

These are files that have parallel rows of "V" shaped teeth. They go from about 16 tpi. down to about 75 tpi. One of those flat knurls in the picture,with 45º teeth,I made by filing the mother knurl. Obviously,you have to be able to do accurate file work to do this. You can feel your way into the last cut you made,and proceed around the circumference.

[george wilson]

There is a narrow knurl just to the right of the blue knurl. This knurl makes a chevron about 3/64" wide. I made it by hand. I filed each side of it with a checkering file at an angle,tilting the file upwards so the grooves would peter out in the center of the knurl. The, I filed the other side. It makes perfect little chevrons.

I was making some parts for an antique for my favorite customer. There were brass ferrules with this chevron on them. I needed a QUICK knurl. It worked surprisingly well,producing identical little chevrons on my replacement ferrules.

[Leigh Betsch]

George thanks a bunch for teaching. Do you just plunge in with the cross slide letting the helix of the tap turn the knurl blank as it hobbs the pattern? or do you engage the feed and match it to the pitch of the tap? I assume you have the knurl blank vertically on center of the spindle? How small of taps have you used? I mostly use 2 flute gun taps, will these work or do you need 4 flute hand taps? Sorry for all the questions but I plan to try this, once my current project is done!

[george wilson]

I neglected to say that you just gradually plunge the rotating knurl into the revolving tap. If the knurl doesn't start rotating when it engages the tap,something is wrong,and the rotating tap will eat out a flat spot and ruin the knurl.

I suppose speed of about 200 r.p.m. works well. Left that out too.

You need 4 flute taps. Your 2 flute will /may not jeep the knurl rotating at all times.

You keep the center line of the knurl on the center line of the pap,or you will make an off center knurl.

IF you can find some OLD 4 flute taps that have a center hole drilled in its end,like the old ones sometime do,you can just use a normal dead center to support the tap.

I have used down to about 6-32 taps. Could go smaller if you are careful to not over stress the tap when hobbing.

[Rick Markham]

That's really interesting George. I'm looking forward to being able to try this in the future. I never would have even considered using a tap to make knurls.

[Justin Bukoski]

George,

I want to thank you for imparting your wisdom in these posts. Some of the stuff you are talking about is beyond my current skill and interest but it makes me feel good to know that this info is captured in a place that I can refer to it in the future. I'm old enough to know that I'm not old enough to know what I'll want to know later. :)

Thanks again!

[george wilson]

I was hoping Ron Brese would see this post. Hope he chimes in before it disappears and gradually gets lost.

My first burst of photos,some months ago,are somewhere around page 111,or somewhere in there.

[Leigh Betsch]

Pics of a couple of rope knurls that I made.
The tap hobbing worked great! I am amazed how easy and controlled the tap hopping was. I really thought I would break at least one tap before I got it right, but it went very well. I used a 10x32 tap to hob the knurl for these knobs. I also hobbed a knurl with a 10x24 tap but I like the finer pitch better.
I made a knurl holder similar to yours George, and a couple of O1 knurls, heat treated with a torch. I'll probably post a few pics of the process in the metal working forum.

Thanks a bunch George!

[george wilson]

I am glad you have tried out the process,Leigh. Just one person learning from the posting has made it worth the effort to put it up.

I have found out that the finer pitch knurls make the best results in brass,from experimenting with a few on some brass cap screws I made for David weaver. The coarser knurl didn't produce as clean a result. At a certain point,the metal gets too work hardened to fully form up into a perfect knurl.

The first bad picture shows a finer pitch knurl that closed up the serrations nice and clean. I made the angled knurl by presenting the blank knurl to the tap at an angle. The second bad picture shows how the brass would not close fully,due to a coarser thread tap being used. I can't recall the threads per inch off hand.

I sent the coarse knrled one to David along with 2 others as it was a favor,and could easily be cleaned up with a triangular needle file to make the knurl sharp. These cap screws also needed to be sanded smooth in a drill press.

[Jeff Wittrock]

I'm glad you brought this thread back to life Leigh. I missed it the first time. Nice looking knurls by the way.
Thanks for posting this George. I don't have a lathe, but still just the kind of stuff I'm always looking for. I'm already thinking on how I could rig something up in my drill press to try something similar, but I can can just see the chuck falling off.

Is this in the "Neanderthal wisdom / FAQs"? If not, I think it would fit right in.

-Jeff

[Leigh Betsch]

I second the FAQs request! Although not necessarily woodworking, it is one of those tricks that is going to get lost in the new world of CNC everything.
I'd like to try some smaller maybe 6x40 or even smaller with multiple ropes instead of one large one. I guess the knurl would still be one rope but multiples on the knob.
I would change one thing on the toolholder next time, or I might modify this one. I'd like more overhang of the knurl beyond the holder, so I could get multiple ropes knurled onto one knob with out the knurl holder interfering.
I have to do a bit of lathe or drill press polishing and I'm sure they would never be appreciated by the Queen of England they are good enough for the girls I go with. Oops that's another thread entirely!;)

[george wilson]

I have a lot of truly oddball taps. Some of them have multiple start threads,and they wind around the tap at about a 45º angle in some cases. No idea what their application was. It would be murder to start some of these taps.

So,I thought I could make some really angled knurls with these very angled taps. Somehow,the multiple thread taps produced knurls that looked like they were made by a single start tap!! I haven't figured out how that worked yet!!

The only way I can make the angular knurls is to see how extreme I can tilt the blank knurl when presenting it to the rotating tap. If I go too far,the tap starts engaging the knurl on the REAR end of its threads,and chews up the knurl. I can tilt about an estimated 20 degrees,or so(I haven't measured the tilt angle).

[Stewie Simpson]

Excellent post George. Your recent postings have been of high value as always. Keep them coming.

Stewie.

[george wilson]

Stewie,since you cannot access the FAQ section,I could re post the pictures of my back saws if you wish in the regular Neanderthal section so you can see them.

[Jim Koepke]

George,

Thanks for posting this.

My metal working is fairly limited to what can be done with files, hammers and hack saws, but I can still dream of one day being a bit more adept.

It is also interesting to know how things are done.

jtk

[george wilson]

Jim,everything on my infill planes posted in the FAQ,except the cap screws,was done with the same type tools. Don't think you can't do much with just those things.

[Jim Koepke]

Jim,everything on my infill planes posted in the FAQ,except the cap screws,was done with the same type tools. Don't think you can't do much with just those things.

Oh I know. I am often amazed at what can be done with limited tools and a little ingenuity.

jtk

[David Weaver]

Jim, you can do like I did and buy the screws from george. Well, I only bought one and I had to fight to get him to take money.

Anyway, the rest of the plane can be done with files, hammers and hacksaws pretty much. Maybe add a medium-aggressive rasp and a carbide scribe, but that's it.

I did not buy much for my first two planes. Well, I really haven't bought much for them since, either. I *know* you have that big piece of granite to clean them up, and presumably you have a machinist vise that can open up at least 4 inches.

I think it's easier (not quicker, but easier) to build the planes by hand because you can just lay out how you want to do things by hand, and then cut the infill close and flush it to the metal by hand. It might not look like a holtey (mine don't) but the plane performance is otherworldy in hardwoods, makes it all worthwhile.

[george wilson]

Johnny Kleso also makes cap screws. He makes them for Brese. I do not want to take his work away.

[Harlan Barnhart]

... It might not look like a holtey (mine don't) but the plane performance is otherworldy in hardwoods, makes it all worthwhile.

David, this is an official request for you to post pictures of your infills. (Or other planes you have made). :)

[David Weaver]

I think two of them are up here already, one kit and one scratch built, and the first one (which turned out to be horrible looking) was on woodnet. I have a fourth in the works now, and enough supplies to scratch build three more (the wood is the hardest to get) but am admittedly dragging my feet a little because I don't really *need* more of them.

I'll see if I can locate the two that I posted on here.

[David Weaver]

http://www.sawmillcreek.org/showthread.php?142446-Another-Infill-A-Kit-this-time

http://www.sawmillcreek.org/showthread.php?139402-Finished-a-New-Plane-Today (i say in the link that it's cocobolo, but I think it's bois de rose, it didn't make me sneeze and was MUCH better to work with than anything I've bought as cocobolo - less oily, nicer to work)

The top one is a kit, but it was worse to do than making from scratch. There were so many shortcomings to the kit (I think i wrote about them in the post) that it really didn't save much time over the scratch plane, and the mild steel was a lot more rubbery on the lap. If it was quicker (i don't remember too clearly how long it took), it was much more frustrating. It is admittedly much better style than my scratch ones, but when I get done with the current st. james bay kit, the next two will be scratch, completely scratch, and I'll do better with design and not use things like the ugly mcmaster car knurled bolt, or round off all of the details instead of faceting them.

(though on the second one here, I threw a lever cap in from brese's parts offerings since it was cheap, and I had already done the lever cap on the first one).

I did also file a chamfer on the sides of the panel plane since the picture, too, like spiers does. I couldn't live with the way the blunt sides looked, even though I was so disappointed with the kit when I took this picture I just wanted to be rid of working on it.

The three infills are by far the best working planes I have. I didn't like the shepherd kit any better than an LN 6 in use at first, but I've learned its quirks now and it's like a freight train. It'll be replaced by a single iron scratch built panel plane, though - scratch save the trick infill screws I got from george.

Like I said, nothing pretty, especially the scratch stuff (the one missing is definitely a lot worse looking than the second one here, but it works well), but cheaper than buying and you have control over the bed to iron fit, the lever cap to iron fit and the size of the mouth.

Having had some discussions and direction from george and a little more sense of what looks good, I'm anxious to get a few nice ones made.

FTR, the second one I put together (i think i mentioned it) with a cordless drill, a power sander, and I believe a couple of shop modified nicholson files from home depot.

[Ray Gardiner]

Hi George,

Thanks for posting that, I'm making some lever cap screws soon, and I want to do a rope knurl, like this one that Peter McBride made.
He hand engraved his knurl from some silver steel, but since he does engraving professionally, I need a simpler method, and your post is exactly what I was looking for.

So many thanks for a timely post.

Here is one that Peter Made,

200990

I like the square threads too. Need to make a tap for that. 1/2" 13 tpi.

Regards
Ray

PS. I did the cast bronze lever cap.

[Leigh Betsch]

I'd love to learn how to make a square thead tap if anyone has the time to post a how to thread.......