• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.

D. Gray D&D - HEAVY DUTY KNURLING TOOL KIT

VicHobbyGuy said:
How long would the bronze nut last, and what would the wear rate be, with normal (thin coat of oil) lubrication?
Click to expand...

I don’t know what the wear rate would be. Perhaps a question for roton? Maybe there is an industry standard accepted wear rate and the 1250lbs operating load refers to that?

Just observational info: taking light cuts (both with turning tools and parting tools) seems to put more pressure on the compound/cross slide than taking a “good bite” (the DoC depends on the material properties). How do I know that? Well, after turning for a good length and returning the carriage back to the beginning of the cut, the tool seems to leave a mark (or drags) on the part with shallow DoC. Not so after a heavy cut. Could be because the tool is working more optimally with a heavier cut - don’t know.

Getting back to knurling: I have an offshore version of the one Craig is currently building. It seems to work really well (axles are a bit lose for my liking though). What I found to work well (in any material) is position the tool on the diameter with the wheels just touching. Apply lots of lube, crank the tensioning bolt quickly and firmly another 1/4 to 1/2 turn to take a real bite (one can hear it “sing”), engage the longitudinal feed and keep lubing. Full depth, one pass. Things get toasty warm, but no harm done in many years of use. Works very well.

This is a 3/4” and a 1-1/4” diameter knurl in mild steel and O1 respectively. Both have been used for 2 years (hence the dirt and slight wear off the peaks).

9FCDB513-80C0-4A39-8990-7B743EB28984.jpeg


E648DCA5-F340-4843-A2B2-D281EAF05522.jpeg
 
RobinHood said:
I don’t know what the wear rate would be. Perhaps a question for roton? Maybe there is an industry standard accepted wear rate and the 1250lbs operating load refers to that?

Just observational info: taking light cuts (both with turning tools and parting tools) seems to put more pressure on the compound/cross slide than taking a “good bite” (the DoC depends on the material properties). How do I know that? Well, after turning for a good length and returning the carriage back to the beginning of the cut, the tool seems to leave a mark (or drags) on the part with shallow DoC. Not so after a heavy cut. Could be because the tool is working more optimally with a heavier cut - don’t know.

Getting back to knurling: I have an offshore version of the one Craig is currently building. It seems to work really well (axles are a bit lose for my liking though). What I found to work well (in any material) is position the tool on the diameter with the wheels just touching. Apply lots of lube, crank the tensioning bolt quickly and firmly another 1/4 to 1/2 turn to take a real bite (one can hear it “sing”), engage the longitudinal feed and keep lubing. Full depth, one pass. Things get toasty warm, but no harm done in many years of use. Works very well.

This is a 3/4” and a 1-1/4” diameter knurl in mild steel and O1 respectively. Both have been used for 2 years (hence the dirt and slight wear off the peaks).

View attachment 25579

View attachment 25580
Click to expand...
Operating loads are generally a factor below material deformation of either threads or nut or nut mounting. As soon as stretch or compression starts the accuracy starts changing, exceed it by a lot, this stops, moments before failure.
 
A good looking project. Peter I agree with your points, but it would be easy to replace the knurled nut with a hex nut. When I've used them, its about no pressure on the feedscrew and nut and no infeed. Crank the tension on the scissor and it knurls in one pass.....but that does require cranking the tension up more than the knurled nut. ( I guess the cranking would impose some force on feedscrew and nut, but most taken by the scissor obviously.)

Maybe how I've used them isn't how this one is to be used, i.e. maybe multi pass (but I can't see a reason to)
 
A little more progress today....


ReamSidePlate.JPG


Reaming the 1/2" swivel saddle on the first side plate. I'm finding the setup for this challenging. Resorted to two pieces of 1/2" brass round stock one either side of the upper lobe. Clearance space between the parallels was pretty tight.

1stSidePlate.JPG



1st side plate done, 3 more to go. All 4 holes get reamed. A lot of collet changes.

UPDATE...

2SidePlates.JPG


I managed to get two side plate done today....
 
Last edited:
Four side plates now drilled and reamed.......

4SidePlates.JPG



Once they are reamed you mill or saw off the top lobes....

RemovingLobes.JPG


Finally each plate needs to be drilled and tapped for a 6-32 grub screw....

6-32Drilling.JPG


Unfortunately I broke my tap while attempting to tap the first one:mad: Off to CT tomorrow.
 
I built one of those 10+ years ago, plans came from a book, spring is a good idea.
Suggestion: Hex nut on top. On mine, it takes quite a bit of pressure on that screw, I can't imagine a brass thumb screw being able to get enough pressure (or for that matter, surviving the pressure). I'm using a 7/16" wrench to tighten up mine
 
cuslog said:
I built one of those 10+ years ago, plans came from a book, spring is a good idea.
Suggestion: Hex nut on top. On mine, it takes quite a bit of pressure on that screw, I can't imagine a brass thumb screw being able to get enough pressure (or for that matter, surviving the pressure). I'm using a 7/16" wrench to tighten up mine
Click to expand...

The kit comes with a hex nut that can be used instead of the brass thumb nut.
 
trlvn said:
"CT" as in Canadian Tire? You might want a better quality tap.

Craig
Click to expand...

I've been waiting for a reply on this question @YYCHM . But I think either you forgot about it or you intended that your thumbs up meant "yes".

Anyway, If you did mean CTire, I'm with @trlvn on this one. I gave up on cheap Crappy Tire / Amazon taps a long long time ago. They cut crappy threads, they don't cut easily, require too much force, and they break way too easily. Sometimes they even cut under or oversize threads. I buy all single high quality taps today. I can't justify full sets so I only buy them as needed.
 
Susquatch said:
They cut crappy threads, they don't cut easily, require too much force, and they break way too easily. Sometimes they even cut under or oversize threads.
Click to expand...
I still have lots to learn. There was an interesting discussion on the 7x lathe group at groups.io recently on taps and tapping.
https://groups.io/g/7x12MiniLathe/topic/taps_from_different/93012175?
I shouldn't have been surprised to learn that taps come in different sizes:
https://www.nextgentooling.com/technical/unc-unf-class-of-fit-tap-tolerance
So that probably explains some of the variation between taps in my collections.
I also didn't know that it's customary to choose the tap drill for the % thread required, generally smaller % for steel and larger % thread for softer materials. Some of the 'hard-to-tap situations I've had resulted from too small a tap drill. BTW, I've also found that my number drills aren't always 'on spec', but I'm not about to order up a $1k set of number/letter drills from KBC - so I do more experiments and tests now. Fortunately I haven't broken a tap in many years, probably because of my timid approach and failing muscle-power! :)
@YYCHM : what % thread does DGray recommend for those parts?
 
I've had some Canadian Tire HSS tap and dies I bought many years ago that actually were not too bad. I've also heard from others that had some positive things to say about them also. I know their product has varied hugely over the years and have seen some garbage their also. I think if they had actual hss tap and die set that appeared to be okay I wouldn't necessarily shy away from them anymore than any other importer. Most lower cost tap and die sets I see now are not hss but rather high carbon steel.
 
Done.... All 4 side plates tapped 6-32....

Tapping6-32.JPG


Switched to a tap handle that provided better feel. Lots of cutting fluid and clearing tapping swarf. No further tap fatalities.

I've had pretty good luck with CT Maximum taps when purchased individually. I do admit they seem kind of pricy though. Convenience rules for me I guess.
 
YYCHM said:
% thread is not specified in plans. I went 7/16" for 6-32 as that's the closest drill bit size I have. The CT Maximum taps suggest 7/16" as well.
Click to expand...
typo- you meant 7/64?
I like the same LMS tap drill chart that @gerritv has posted.
As he said, for steel, with 50% thread the recommended #32 drill is .116"
7/64 is .109", smaller than a #35 drill
I can definitely feel the difference that even one step in the number drill series makes when tapping.
Even my bargain number drill set is extremely useful, so I'd suggest keeping a lookout for a set on sale.
I also find it handy to have a chart listing fractional, number and metric drill sizes:
 

Attachments

Got started on the swivels today....

Swivels1.JPG


The round stock is supplied as a single piece, so you have to cut it half and turn the resulting pieces down to final dimension.
 
You must log in or register to reply here.
Back
Top