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View Full Version : How do you knurl with a QCTP



Elninio
05-27-2013, 09:25 PM
http://www.use-enco.com/ProductImages/0906081-24.jpg

I've never needed to do hash knurl; it was always just straight lines. I noticed that these knurling holders aren't adjustable, so how do you produce strongly defined hash patterns?

JoeLee
05-27-2013, 09:35 PM
You have to center it, meaning that the center line of your work has to exactly centered betwen the two knurls.

JL................

dalee100
05-27-2013, 09:39 PM
Hi,

You push really hard.

The general consensus is this style of knurl tool is hard on the lathe cross slide and compound because of the pressure needed to impress the pattern on the material. With smaller home shop lathes I do agree. But with bigger commercial machines, I'm not so sure. In any case, knurling isn't all that common of a operation for most machinists. So it might be a less concern than we sometimes make of it.

I personally use squeeze type knurlers.

dalee

spongerich
05-27-2013, 09:48 PM
I have one that came with my QCTP and a smaller squeeze type one. The squeeze one is definitely a bit easier to use and requires a lot less feed force to make a good knurl.

vpt
05-27-2013, 09:59 PM
I just made a special BIG tool holder to hold my old style lantern tool post knurlers.

Elninio
05-27-2013, 11:40 PM
You have to center it, meaning that the center line of your work has to exactly centered betwen the two knurls.

JL................

Yes but the knurl spacing must be a multiple of the circumferance, so ..?

MichaelP
05-28-2013, 12:14 AM
Yes but the knurl spacing must be a multiple of the circumferance, so ..?Ideally, knurl pitch should match the circumference. Don't worry about spacing.

Everything else aside, this is the worst type of knurler, IMO, but it's worth trying if you have nothing better.

becksmachine
05-28-2013, 12:56 AM
Look at it this way.

A 30 pitch knurl has a lead of .033". In 200 pitches (≈ 2" diameter), each tooth would have to gain (or loose) only ≈.000075" to make up a difference of .016" on the circumference.

Dave

JoeLee
05-28-2013, 07:13 AM
Yes but the knurl spacing must be a multiple of the circumferance, so ..?

Yes, true but with diametreal pitch knurls, and I think that is what they are called........... as long as your OD is an even dimension, example, 1", 5/8" 11/16" etc. they will work just fine.

But as mentined, it takes a lot of force to displace the surface of the work, something you don't want to do on a small lathe.
However, some of that force can be over come by slightly angleing the knurl so the edge of the wheel bites in vs the whole surface.

JL.......................

Rich Carlstedt
05-28-2013, 01:21 PM
Yes but the knurl spacing must be a multiple of the circumferance, so ..?

Exactly !

Two things
First ,the style of holder shown above should be started with only a partial knurl , say a width of .060 , and then the knurler fed to the left slowly
to minimize the load on the Cross-feed screw/nut. Also this style requires the use of a tailstock center.

Second, the diameter needs to be adjusted to match the knurl pitch. Most machinists plunge in, until the knurl matches the pattern
needed on the part. When the knurl pattern approaches a close point, the knurl form roller can slip a small amount to keep the pattern in sync.
You may note that sometimes you have a nice pattern, but not sharp points. Trying to go deeper means having either slip in the rollers, or a screwed up pattern.

Here is a photo of an operating valve I made.
The valve body is 1/4 inch in diameter, the flared copper pipes are .060 ( 1.5 mm) in diameter and the flare nuts are scale.
The knurled cap ( .160") was made with a .100 pitch knurler. A standard knurler on an Aloris holder.
Note the pitch on the knurl produced is about .020 , which is a 5 start knurl before repeating.
By reducing the diameter .002 at a time, I was able to find the magic point that produced the scale knurl using a course knurling tool.
For newbies, The knurl roller came around the part and missed the original mark, and made a new mark about .020. this repeated about 4 times and then it entered the original mark
Because the diameter was controlled a distinctive knurl was created. This cannot be done by plunging in -you must start a small area and when the pattern develops, then feed to the left
So multi-starting a knurl can work to your advantage !
Rich



http://i273.photobucket.com/albums/jj220/StationarySteam/Monitor%20Engine/MonitorTricockValve_zpse6562c08.jpg (http://s273.photobucket.com/user/StationarySteam/media/Monitor%20Engine/MonitorTricockValve_zpse6562c08.jpg.html)

Lew Hartswick
05-28-2013, 01:34 PM
Yes but the knurl spacing must be a multiple of the circumferance, so ..?
This has been disproved many time over. All that is required is
increase the pressure while turning till the knurls track. I've
done it with scissor tools using diamond knurls lots of times on
any diameter materials. Most often it was aluminum but on
occasion steel.
...lew...

beckley23
05-28-2013, 01:53 PM
Both of the pieces shown are 303SS, and were done using a scissor type knurling tool. They are not the same diameter. BTW, nobody has mentioned it, but do this with coolant if you want the best results, you do get some flakes that need to need to be flushed.
The parts are the knob and a "minute" dial for a TA adjuster.

http://img.photobucket.com/albums/v152/beckley23/100_0399_zps034d752a.jpg

To answer the OP's original question. I have had to use one those knurling tools shown on a 16" Monarch lathe. It wasn't easy, nor was it fun. Do yourself a favor and get a scissor type knurler. One of the problems with the bump type tool, unless the knurl is centered on the toolpost clamp screw, the toolpost will want to rotate. It's happened to me acouple of times, not often, but I do make sure the clamping screw is extra tight.
Harry

Frank Ford
05-28-2013, 02:34 PM
As much as it's logical to be careful to match the diameter of the part and the pitch of the knurl, I still don't find myself doing that. I'll admit that most of my work is fairly loose when it comes tolerances. In fact, I guess I have a high tolerance for low tolerance, as long as I get the job done. (Too much woodworking in my past, I'm sure.)

With that preamble, I've only ever knurled one thing where the final diameter was critical - a coarse diamond knurl on 1/4" steel. Except for that one job, I've always relied on the "magic" to get the job done. I set the knurl to center, plunge in until I get a good pattern, and call it done. Look at my work with a loupe and you'll might see some unpleasant stuff, but to the naked eyeball, it looks pretty good to me. Here's an example, with a single knurling roller - I did not calculate anything - I just pushed it in until things looked right:

http://www.frets.com/HomeShopTech/Projects/AXAKnobs/axaknobs09.jpg

And, I do squirt a stream of cutting oil to flush the chips.

By the way, it's easy to set the nonadjustable double knurl to center. Just bring it in to the work, turn the spindle by hand and tighten the tool post as you feel how the rollers are making contact with your finger, then when you start up you can see the pattern starting and you can raise or lower the tool to get an even pattern with each roller.

I really don't quite get the business about "bump" or pressure knurling being hard on the lathe. I assume that simple turning often puts a pretty heavy load on the bearings and cross slide, and really, how much time to you actually spend knurling anyway?

Now, for knurling small diameter or long pieces, that kind of tool can easily bend the work, so I'm a big fan of scissor knurls for that reason as well.

Here's my best tip on knurling: Take a stroll around your shop and look carefully at the knurled items you'll find there - knobs, nuts, tool grips, etc. If your stuff is anything like mine, you'll find any number of high quality tools with slightly (or not so slightly) uneven, incomplete, or otherwise less-than-perfect knurling that you hadn't noticed before. Once you notice the variances in quality from producers like South Bend, Starrett, etc., you may find it less difficult to please yourself, and you can just "go for it" and get on to the next project.

OK, maybe this isn't he place for "lowered expectations," but I do think that striving for perfection can be overdone.

sasquatch
05-28-2013, 08:37 PM
Very good post Frank, and so true!!

J Tiers
05-28-2013, 09:45 PM
It seems that diamond, or skew, knurling will conform to the size of the part nicely.

Straight knurling I have had trouble with if I didn't get it pretty close to an ideal size... that sort of knurl hasn't as many ways to slide to fit, it pretty much looks like a gear. I expect that small errors get washed out even with straight knurls, though, so within limits any knurl will make itself fit.



I really don't quite get the business about "bump" or pressure knurling being hard on the lathe. I assume that simple turning often puts a pretty heavy load on the bearings and cross slide, and really, how much time to you actually spend knurling anyway?


Well, maybe you don't, but I do.... I find that using that sort of knurl takes more force than turning does.... Since when does turning ever take real "C-clamp type" force exerted by the crosslide screw? If it ever does, that would mean your tool quit cutting, and you didn't notice.

Getting a deep well-formed knurl on steel sometimes seems to take a lot of force, far more than I would ever exert with a cutting tool. As for the downward force, I think that also is less, but I have no screw to turn against it, so I cannot be certain.

Remember, you are work-hardening the steel as you knurl.

DR
05-28-2013, 10:08 PM
As others have said the blank diameter is immaterial with scissor knurling tools. We routinely do soft materials, Delrin for one, up to harder material like 304 SS, with no tracking problems.

The only time starting diameter is an issue is when a print specifies an OD diameter of the finished knurl. In that case we've found consistent close OD diameters can only be achieved by taking a fine skim cut over the finished knurl to bring it to diameter.

Advice to the OP, throw that knurl tool in the recycle bin and get a scissor type. You'll never regret doing it.

Frank Ford
05-29-2013, 02:01 AM
Well, maybe you don't, but I do.... I find that using that sort of knurl takes more force than turning does.... Since when does turning ever take real "C-clamp type" force exerted by the crosslide screw? If it ever does, that would mean your tool quit cutting, and you didn't notice.

Getting a deep well-formed knurl on steel sometimes seems to take a lot of force, far more than I would ever exert with a cutting tool. As for the downward force, I think that also is less, but I have no screw to turn against it, so I cannot be certain.

Remember, you are work-hardening the steel as you knurl.

Reckon I was thinking about the heavy downward force on the tool bit as it takes a deep cut, rather than the inward force from the cross slide screw.

Jaakko Fagerlund
05-29-2013, 04:05 AM
Two words: cut knurling <3

J Tiers
05-29-2013, 08:13 AM
This ^^^^^^^

Spin Doctor
05-29-2013, 09:06 AM
IMO Cut Type Knurls are the way to go with smaller lathes typical of the home shop. Second is the Squeeze or Straddle Type. SPI used to carry a couple of Hand Knurlers that actually worked pretty well. I'll try and find a link

DR
05-29-2013, 09:20 AM
IMO Cut Type Knurls are the way to go with smaller lathes typical of the home shop. .......................................

Typically more expensive than the usual home shop lathe.

Jaakko Fagerlund
05-29-2013, 09:30 AM
Typically more expensive than the usual home shop lathe.
That is why one should make it as a project :) Plans are available and published is HSM.

Frank Ford
05-29-2013, 02:22 PM
Typically more expensive than the usual home shop lathe.

Not if you go to eBay and look for the Hardinge cut knurling tool:

http://www.ebay.com/itm/Hardinge-Diamond-Knurl-Tool-Holder-L20a-/321132192842?pt=LH_DefaultDomain_0&hash=item4ac4f8644a

rohart
05-29-2013, 03:09 PM
I really don't know why anyone ever invented the scissors type knurler.

I don't know the name of the kind I like, maybe cantilever knurler ?

In this thread, in post 10, is a picture of the kind of knurler I approve of:

http://bbs.homeshopmachinist.net/threads/58729-Making-quick-change-tool-post-holders-%28picture-heavy%29?highlight=knurler

I prefer a larger one, with a bracket to take the side forces.

The force you have to put into the clamp screw is a quarter what you put into the screw of a scissors knurler. You get so much more control, and it must be one of the simplest tools to rustle up.

DR
05-29-2013, 08:15 PM
I really don't know why anyone ever invented the scissors type knurler.

I don't know the name of the kind I like, maybe cantilever knurler ?

In this thread, in post 10, is a picture of the kind of knurler I approve of:

http://bbs.homeshopmachinist.net/threads/58729-Making-quick-change-tool-post-holders-%28picture-heavy%29?highlight=knurler

I prefer a larger one, with a bracket to take the side forces.

The force you have to put into the clamp screw is a quarter what you put into the screw of a scissors knurler. You get so much more control, and it must be one of the simplest tools to rustle up.

You lost me here, what you show in the linked thread is what I would call a scissor type. A bit different than the usual, but still the same principal.

For most of our production knurling we used a B/S model similar to yours except the adjusting screw and wheels are interchanged, wheels at the out board end and adjusting screw near the mount. That way you can approach from the side or the end.

Another type we use if the job permits is a round shank style, with a "U" shaped yoke on the end with opposing knurl wheels opposite each other. Same low stress on the machine concept.

BTW, we knurl dry if possible, some jobs are totally run dry. Sometimes we'll program a short blast of coolant onto the knurl head to lubricate the axles, otherwise dry works as well as wet IMO.

The knurl tool moves onto the work as fast as reasonable and back off as quickly. You want the minimum number of revolutions of the work with the knurl idling on the work.

Also, aluminum is nasty stuff to knurl, it flakes a lot and those flakes become embedded into the knurl. And, usually will break loose at some future time.

Elninio
05-29-2013, 11:53 PM
IMO Cut Type Knurls are the way to go with smaller lathes typical of the home shop. Second is the Squeeze or Straddle Type. SPI used to carry a couple of Hand Knurlers that actually worked pretty well. I'll try and find a link

Can i take my old knurls and grind them flat into cut knurls? If I want to produce a straight knurled pattern, can the cut-knurl be non-inclined?, but tilted? Or do I have to get an inclined knurl like in the following pic?
http://accu-trak.com/holders_cuttype/mfs21.55_%20modified.jpg

Jaakko Fagerlund
05-30-2013, 04:03 AM
Yes, you can grind the knurler to get it sharp on the edge and use that as a cut knurler. Nothing special in them, works just like any cutting tool.

Elninio
05-31-2013, 12:02 AM
Does it have to be a knurled ( angled ) knurl like a shear tool, for it to work like a 'cut knurl' ?

JRouche
05-31-2013, 12:59 AM
While looking for info on what the "cut type" knurls were and how they work differently I found a nice page with some very nice tech advice. JR

http://accu-trak.com/technicalinfo.html