Knurling tool photos for Kerrin Galvin

[Kerrin Galvin]

Hi Norm,
That a shame on the banning. Did you try the link? You don't need to be a memeber to view.

Gerri's,
That looks to be coming on nicely! Keep up the good work.

Cheers Kerrin

 

[gerritv]

And we are done. I am calling this a success although I still need to read up on depth of cut on some of the commercial vendor sites.
I will be cleaning up the sharp edges and blackening the tool etc. but very happy with the results. The 30° angle results in almost square knurls. I used manual feed, .015 in feed. Powered feed might result in better quality but for most things this works great.
Because of the angle I ran a 10-32 SHCS in from the top of the carrier head. Once adjusted it doesn't need to be done again.

I will order a diagonal wheel to see if I can make a carrier head to do straight knurls as well.

Thank you bazmak for the excellent design, much easier to make than some of the other examples out there.

 

[Kerrin Galvin]

Hi Gerrit,
Looks good! They work extremely well don't they?
Guess I should've just made mine as a block to fit a standard tool holder, as you have done, it would have been lots cheaper! But it reduced the overhang & I'm happy with mine.

Cheers Kerrin

 

[gerritv]

If I had a larger 60° dovetail cutter then it would have been direct mount for me as well. But didn't want to put the project on the shelf while waiting for a cutter to arrive.

 

[bazmak]

Good on you both and glad it works well.If you read my thread you see
i started with the basic idea and not knowing the results.First was a fabricated holder from angle and flat welded together.This proved the concept and proceeded
to work thru various holders from solid blocks to clamp in the 4 way toolpost
before arriving at the current model.with different heads and various bodies
to suit the QCTP etc. During my experiments i found that the depth of cut was
about 15 thou for fine knurls to about 35 thou for coarse knurls. For short knurls i prefer hand feed,with a single pass on alum and brass and a couple of passes on steel etc. Hand feed in AND out gives a crisper knurl to brass
As you say the additional angle gives more of a square knurl.I just angle the wheels at a nom 2/3o,to give a diamond pattern.This also gives a lead in
for the in cut and and a nice bite/finish cut on the out.No doubts lots to learn
so enjoy playing about and please keep this post going.What i like now that most things are sorted is that i have a no of tools i can just pick to suit and know i will get a consistant good quality knurl without straining the lathes. Speeds between 150 and 250 rpm
I finished with lots of bars of different materials which i gradually used up. I found it better to knurl first before finish turning

 

[Nick Hulme]

There must be a missing factor in the design because it works but manages to make Cut Knurling look like not-so-good Formed Knurling.
I'm guessing that the issue is angle because my Cut Knurling tools need adjustment for diameter and can produce poor knurling if not correctly adjusted,

- Nick

 

[gerritv]

I'm still learning about depth of cut and feed rate so perhaps there will be improvement. Although I don't expect commercial quality, I can at least produce 'acceptable to me' knurls for the first time

I agree on the lack of adjustment being a potential problem beyond some diameter range. I have however seen commercial cut knurling tools with no adjustment either, I think Dorian has a range of 3 to cover the diameters?
Overall this type of knurling is very sensitive to the wheels being centered accurately, every style/brand emphasises that.

Edit: Having just re-read the Dorian catalog, there is a lot of guidance there on how to re-design the carrier head for more predictable knurls. For now mine is 'good enough' but will very likely revisit with a new carrier head at some time.
http://www.doriantool.com/wp-content/uploads/SEC-H-Knurling-Tools_LowRes.pdf

Gerrit

 

[bazmak]

I have no idea how much the Dorian is,but guess at 100s of dollars
I am happy with mine for the price.As you say its much better than
a crush knurl but not as proffessional as a dorian

 

[gerritv]

USD600-900 for the Dorian. Never going to happen here
But, much can be gleaned from their catalog.

 

[Wizard69]

I'm still learning about depth of cut and feed rate so perhaps there will be improvement. Although I don't expect commercial quality, I can at least produce 'acceptable to me' knurls for the first time

This brings up an interesting question have you seen any reference on how to calculate feed rates for such knurls?

http://www.doriantool.com/wp-content/uploads/SEC-H-Knurling-Tools_LowRes.pdf

Gerrit

Interestingly I downloaded that catalog last week at work, looking for dovetail cutters.

 

[WOB]

There must be a missing factor in the design because it works but manages to make Cut Knurling look like not-so-good Formed Knurling.
I'm guessing that the issue is angle because my Cut Knurling tools need adjustment for diameter and can produce poor knurling if not correctly adjusted,

- Nick

BINGO! For some reason this entire thread has the knurl cutters being dragged backwards so the teeth contact the workpiece first rather than the flat edge of the cutter as is required for true cutting.

WOB

Cut knurling is made like this:

View attachment CUT_KNURL_2017_10_09_21_27_10_230.PDF

 

[bazmak]

you are correct.I have had the wheels set to lead in which does not cut efficiently however the feed back out does then cut properly to produce a crisp knurl.Next time i will reverse the lead angle from positive to negative so
the main cut is taken on the feed in and also check if its better to wind the tool out after the infeed cut. My knurl wheels also have a sharp corner,SOME DONT
but i have thought of grindinding tie leading face to improve the cutting corner
So far i am happy with the results however there is always room for improvement,glad to see others putting some thought in to it

 

[Nick Hulme]

Single wheel cut knurling tools are simply adjusted for height so the cutting takes place on centre.
Add a second wheel spaced around the diameter and it's possible to see that the angle of presentation and spacing of the two wheels must be different for different sizes of stock, if optimum cutting alignment of the wheels is to be maintained.

- Nick

 

[bazmak]

On my original thread i used from 12 dia to 50 dia on different types of
metal.Some produced better knurls than others.With the wheels set almost touching it cut between the range shown.However i realzed theat there is an optimum angle to be formed by a combination of wheel centres/positions
and barstock dia..I did not proceed any further with trial an error as most
knurling would be done between these sizes and making the wheel centres
adjustable would be complicated.As i said i would love for anyone to try different ideas and post results

 

[gerritv]

Except that Dorian does not adjust the angle of the cut wheels for the range of .5 to 1.5".
Indeed the way Bazmak, Kerrin and I built our versions we are not cut knurling in the usual sense. But is is an approximation that produces ok knurls.

I had a very close look at page H28 of their catalog. The rake is 15°, the angle between the wheels is 60°. Using .5" wheels they get the .5-1.5", .75" wheels for the range 1"-5" and 1" wheels for 2"-5". Essentially the spacing between the wheels increases to get the range. You can do a screen shot of an enlarged section of their catalog page and determine the relative dimensions empirically etc.

I will be remaking my tool, the present one will become yapw (yet another paper weight) Thankfully I don't have too many of those yet
I should have it done sometime next week, there are a few other projects in the way.

 

[gerritv]

This brings up an interesting question have you seen any reference on how to calculate feed rates for such knurls?

The first 20 pages to the Dorian catalog has a wealth of information on knurling, this would apply to both cut and crush knurling. Covers diameter of work, SFM ranges, depth calculations etc.

 

[bazmak]

Also just realized my last statement is incorrect.Changing the lead angle
does nothing.With the wheels set as shown then its the outfeed that
does the best crisp cutting.Reversing the wheel angles will then produce the best cut but the cutting forces will be trying to force the wheels off the pins
These thoughts crossed my mind but i did not want to go down this pathe
as i was happy with the results i was getting
Also thought about grinding 2 chamfers on a pair of knurling wheels to give
a smaller cutting area,but again went on to other things.If anyone feels
like throwing some time and effort and share results then i will share copyright

 

[WOB]

If anyone wants to make a real cut knurling tool similar to the Dorian tool, Home Shop Machinist magazine, March thru Dec. 2010 contain the construction dwgs. and instructions. It is somewhat complicated to build, requiring 3 small gears to be made or purchased, but is no more of a challenge than many of the simple motors we build. I do believe the author over-complicated the design somewhat by specifying ball bearings for the wheel shafts. All the commercial tools I found on-line appear to use simple bronze bearings instead and I have found that it works perfectly well. After all, RPM is low and the cutting oil provides more than sufficient lube for the hardened steel knurl cutters running against bronze thrust washers. The tool provides synchronized adjustment of the cutter spacing to accommodate different work piece diameters. Once you get the hang of it, it will produce excellent quality knurls in brass, aluminum, and soft steel.

WOB

 

[gerritv]

The Dorian style does not have adjustable pivots, the AccuTrak, Hardinge and Zeus ones do. The article you mention is in essence a Zeus clone.
Personally for hobby use I find that version excessively complex. The Hardinge style is much simpler and just as effective (to quote a good friend of mine who has one of each). Several build articles exist for those simpler ones, e.g http://www.gadgetbuilder.com/Cut_Knurler.html and http://www.practicalmachinist.com/vb/general/cut-knurling-how-done-138092/index2.html

This page describes the build of the one in HSM http://thebloughs.net/cut-knurling-tool/

I will post some drawings of the replacement carrier head for Bazmak's style as soon as I dust off my CAD skills a bit. In the meantime a doodle of my new version is attached:

 

[Nick Hulme]

Except that Dorian does not adjust the angle of the cut wheels for the range of .5 to 1.5".

Not being adjustable is the reason for it having such a narrow range.
My large Integi knurling tool covers a range of 5mm to 250mm ;-)

- Nick