Scissor knurl attachment question

[Uncle Buck]

The wife and kids really came through for me for fathers day. They bought me this scissor knurl from Enco. http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=950782&PMAKA=505-4518 Now for the question, several times over the last few years I have read posts on machinist web sites that essentially said if you buy one of these import scissor knurls you needed to immediately replace the knurls that came with the attachment because they are low quality and do not perform well. So the question is what should I get. I know there are multiple patterns and it all depends upon the one you pick. I can easily find replacement wheels of the size my attachment came with but what brand and style should I buy? At least give me the brand I should buy if nothing else, I can likely figure the pattern out on my own. Thanks for the help guys

 

[Ray C]

Hey Uncle Buck...

You might want to give the stock wheels a shot before you give up on them but, if they prove to be yucky, here's the size you need. Same ones I use.

http://accu-trak.com/knurls_convex/kpv.html

And thanks to Darkzero for introducing these to me. Make sure you get 1 LH and 1 RH per set. They're a little pricey (about 28 bucks each) but are precision cutters and made very well. Very unique edges that have a contoured spiral that allows the cutter to stay on track as you dig deeper.

Ray

 

[geotek]

Like ray said, give the knurls you have a chance.
A few pointers. Lube the knurls with a good high pressure oil when running them. I keep an oil can with some 30 wt Rotella in it and soak the knurl real well at the start. When starting the knurl, stay in one place and keep increasing the pressure until the knurls find the best depth and start tracking nicely. Then you can reduce the pressure a bit and start moving along the workpiece. Knurling can be tricky, and it takes some practice to get it right.

 

[Uncle Buck]

I appreciate the guidance. I became sold on the scissor style knurler a few years ago when I had the chance to use one on a project in a night class at my local tech center. I agree there is a learning curve to them and it is easy to get less than best results until one has learned the ropes of using one. Shortly after taking the class I used the knurling toolholder that came with my Phase II QCTP set to apply a knurl to a project I was working on. I decided right then I would never use a knurling tool that relied solely on pressure applied from crossfeeding the compound again on my Atlas lathe. After doing that just the one time I was convinced that repeating that it would not take long to wear out the brass nuts used at the cross slide and the compound if I recall correctly. I was most uncomfortable with the amount of pressure it took to apply a decent knurl to a piece of steel this way. This is one example of having to make allowance for one of the several shortcomings of Atlas lathes. As has been noted numerous times by others and is widely accepted as a fact, Atlas machines are a good bit lighter than other brands in their size range and simply cannot handle some of the same processes or applications the heavier brands such as a South Bend, or Logan can. Although, while many of the other heavier lathes can better withstand the stress of applying a knurl with a side pressure applied knurl tool without complaint it is undeniable that really any brand or type of lathe can benefit from the reduced stress on the machine that a scissor type knurler imposes.


I am really looking forward to fitting this attachment to my machine and putting it to use. Thanks for the tips on use and where to turn for replacement knurl wheels if I need to. I suppose it would not hurt to simply use what came with the attachment first to see how it performs before ditching them for replacements. Great idea and suggestion.

 

[Ray C]

Atlas or not, there's no way I would use a traditional knurler anymore. That has got to be applying 20-30 times the pressure of a lathe bit cut -at least that much and possibly (probably?) more. With a scissor type, you're putting some torque through the compound but I can live with it for the small amount I do. It's also a little harder on the carriage travel rack gear -tolerable and probably inconsequential.


Ray

I appreciate the guidance. I became sold on the scissor style knurler a few years ago when I had the chance to use one on a project in a night class at my local tech center. I agree there is a learning curve to them and it is easy to get less than best results until one has learned the ropes of using one. Shortly after taking the class I used the knurling toolholder that came with my Phase II QCTP set to apply a knurl to a project I was working on. I decided right then I would never use a knurling tool that relied solely on pressure applied from crossfeeding the compound again on my Atlas lathe. After doing that just the one time I was convinced that repeating that it would not take long to wear out the brass nuts used at the cross slide and the compound if I recall correctly. I was most uncomfortable with the amount of pressure it took to apply a decent knurl to a piece of steel this way. This is one example of having to make allowance for one of the several shortcomings of Atlas lathes. As has been noted numerous times by others and is widely accepted as a fact, Atlas machines are a good bit lighter than other brands in their size range and simply cannot handle some of the same processes or applications the heavier brands such as a South Bend, or Logan can. Although, while many of the other heavier lathes can better withstand the stress of applying a knurl with a side pressure applied knurl tool without complaint it is undeniable that really any brand or type of lathe can benefit from the reduced stress on the machine that a scissor type knurler imposes.


I am really looking forward to fitting this attachment to my machine and putting it to use. Thanks for the tips on use and where to turn for replacement knurl wheels if I need to. I suppose it would not hurt to simply use what came with the attachment first to see how it performs before ditching them for replacements. Great idea and suggestion.

 

[Uncle Buck]

Atlas or not, there's no way I would use a traditional knurler anymore. That has got to be applying 20-30 times the pressure of a lathe bit cut -at least that much and possibly (probably?) more. With a scissor type, you're putting some torque through the compound but I can live with it for the small amount I do. It's also a little harder on the carriage travel rack gear -tolerable and probably inconsequential.


Ray

Yup, could not agree more! I had no idea of how much more pressure but I was quickly able to tell it was a heck of a lot of pressure/abuse!

 

[Video_man]

I bought this same knurl tool about 12 years ago, so maybe it's improved by now. But I had to re-build it---the main axle was a poor fit, which let the arms twist, and the press-in axles for the knurls themselves were enough smaller than the hole in the knurls that they also could move. It let the knurl cut a sort of inclined, or spiral, knurl pattern. I replaced them with better-fitting pins and that did the trick. The knurls themselves were ok, but appear to be metric so figuring out how many knurls-per-inch (I use a calculation program to find the proper turned diameter for the work) was a little tricky. (I inked the knurls, ran out a 10-inch pattern, counted the marks and divided by 10, if anybody cares)

 

[Ray C]

BTW: The pins that the rollers ride on must be hard -as in real hard! With soft metal, any swarf that gets in there will grind a regular steel pin to mince meat in no time and then the wheel won't stay flat and have the problems you experienced.

Ray

I bought this same knurl tool about 12 years ago, so maybe it's improved by now. But I had to re-build it---the main axle was a poor fit, which let the arms twist, and the press-in axles for the knurls themselves were enough smaller than the hole in the knurls that they also could move. It let the knurl cut a sort of inclined, or spiral, knurl pattern. I replaced them with better-fitting pins and that did the trick. The knurls themselves were ok, but appear to be metric so figuring out how many knurls-per-inch (I use a calculation program to find the proper turned diameter for the work) was a little tricky. (I inked the knurls, ran out a 10-inch pattern, counted the marks and divided by 10, if anybody cares)

 

[Video_man]

@Ray, good point. I replaced the provided pins --- Asian cheese-steel, although they did not appear worn, they were too small out of the box---with dowel pins. Fortunately a good fit, as they are (as you point out) hard.

 

[benmychree]

Yes, the scissor type knurling tools are wonderful, and save a lot of wear and tear to the machine, especially the smaller lighter ones, which as has been pointed out, can be literally ruined by straight in knurling. I looked at the site that sells the convex knurls, and they look like a good thing, but I can add one thing to that discussion; note that they have both circular and diameteral pitch knurls. As I understand it, the diameteral pitch are best for standard fractional and inch sizes, the circular pitch are best for odd sizes or perhaps decimal sizes; this helps them to cut a clean knurl without possible double tracking and making a mess of your project.