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Cut-off blades for old Armstrong holder?

pchp

Plastic
Joined
Oct 8, 2019
Hi.I bought some 5/8 x 3/32 cut-off blades but they don't fit in my holder.
They are square on the edges and it seems that the holder need blades cut at an angle.
Where can I get those blades?

IMG_6228.jpg
 
The old Mo-Max bits I've seen from the Cleveland Twist Drill Company had the tapered-bottom style if I'm not mistaken. Not sure where to find modern replacements. McMaster sells bits with a tapered *body*... not sure about the tapered bottom though. Crucible (Rex 95, etc.) and Armstrong stuff might also work since those were contemporary.

Let me double check... see if I can get a picture.
 
Who sells cut-off blades that aren't tapered (or some other kind of side relief)?

Ayup. Those are tool blanks not parting blades. I suppose, 'a tool blank to make a parting blade from', might be accurate.

All is not lost, however. Play around with a protractor and see what angle you need. Gonna be between 3 and 7 degrees. Play with the rest on a bench grinder to get pretty darn close to that, and dress down one side.
I found a set of Vice-Grips and using them to clamp another tool bit, on to the rest of the grinder allowed a fella to keep a pretty steady and even grind on.

Flip the tool blank around, adjust the clamped down tool bit a bit closer to the wheel, and do the other edge.

I have done this with cut off blades that were too wide to fit my holders, plus for some holders I made. Worked well.

As I recall, I set the clamped guide at an angle so as I fed the tool blank across the rest, it only really ground on the edge of the wheel face. You can tap the clamped guide with a chunk of bar, and creep it in a wee bit closer at a time between passes, and you get a pretty nice, straight edge, with a bevel.

If you are going to err on the angle, make it so the blade squeezes in towards the holder, rather than wedging a sharp edge into it and reducing the stiffness.

You will still have to grind some side relief on the parting blades, but you will at least, get to use what you bought, if only after a little rework.
 
Ayup. Those are tool blanks not parting blades. I suppose, 'a tool blank to make a parting blade from', might be accurate.

All is not lost, however. Play around with a protractor and see what angle you need. Gonna be between 3 and 7 degrees. Play with the rest on a bench grinder to get pretty darn close to that, and dress down one side.
I found a set of Vice-Grips and using them to clamp another tool bit, on to the rest of the grinder allowed a fella to keep a pretty steady and even grind on.

Flip the tool blank around, adjust the clamped down tool bit a bit closer to the wheel, and do the other edge.

I have done this with cut off blades that were too wide to fit my holders, plus for some holders I made. Worked well.

As I recall, I set the clamped guide at an angle so as I fed the tool blank across the rest, it only really ground on the edge of the wheel face. You can tap the clamped guide with a chunk of bar, and creep it in a wee bit closer at a time between passes, and you get a pretty nice, straight edge, with a bevel.

If you are going to err on the angle, make it so the blade squeezes in towards the holder, rather than wedging a sharp edge into it and reducing the stiffness.

You will still have to grind some side relief on the parting blades, but you will at least, get to use what you bought, if only after a little rework.

Thanks. I am going to try :scratchchin:
 
Worth noting that not all tool steels are created equal.

I've found that the metallurgy of Chinese "tool steels" is generally sub-par to that of American and European made stuff. Bear this in mind if you find that you're having difficulty maintaining a sharp cutting edge.
 
If you holder is a Armstrong No. 20 I have some new old stock Armstrong blades for it. See pics attached ( I hope )
Shipping may be costly though. The drawing is an exaggerated view of the profile looking from the non cutting end. If your holder is a different model I may have the correct blades as well as I have about 30 lbs. of unused old HSS parting blades. Sam
ASBlade.6-4.jpgASBlade.6-1.jpgASBlade.6-2.jpgASBlade.6-3.jpg
 
If you holder is a Armstrong No. 20 I have some new old stock Armstrong blades for it. See pics attached ( I hope )
Shipping may be costly though. The drawing is an exaggerated view of the profile looking from the non cutting end. If your holder is a different model I may have the correct blades as well as I have about 30 lbs. of unused old HSS parting blades. Sam
View attachment 323026View attachment 323027View attachment 323028View attachment 323029

Yes, I have an Armstrong No. 20. That is what I was looking for. I send you a private message
 
Armstrong 2020R Cutoff Tools

Although late (again) to the thread, thought I'd add some pics of the much aligned Armstrong tool(s) in my possession.
These are Armstrong #2020-R and hold a blade that tapers from 0.1 to 0.065.
Pretty sure these were ground by my pops back in the 60's and I really haven't had a reason to grind any new ones as these
work fine with an occasional sharpening before using. The finish between the two are noticeable. Perhaps one is a knockoff
or the line worker was having a bad day. Cheers.

PMc

View attachment 323067 View attachment 323066 View attachment 323068 View attachment 323069
 
I don't mean to hijack - but just out of curiosity would you happen to have any in 1" x 1/8" size?

1/8" is usually for 7/8" blades at least that is what my old Armstrong catalog says. I have 1" X 3/16" in a couple varieties such as Latrobe Double Six M-2 that are ground finish and are ground for old style RH Or straight tool holders but work fine in my CA Aloris style holder, the actual height is a little over 15/16" and 8" Long. Have Armstrong in the same dimension but 6" L, they look like the smaller ones in the photo I posted and are a black finish and are for RH or ST holders as well. Also have Clarite By Columbia Tool Steel Co. HSS that is 1" X 3/16" with a black finish, these have more of a flat profile on the top and bottom and not specifically for a RH or LH holder. $10.00 each if you purchase more than one plus shipping, can post photos later if needed. These are all old unused condition with a few stains from storage. Sam
 
If you holder is a Armstrong No. 20 I have some new old stock Armstrong blades for it. See pics attached ( I hope )
Shipping may be costly though. The drawing is an exaggerated view of the profile looking from the non cutting end. If your holder is a different model I may have the correct blades as well as I have about 30 lbs. of unused old HSS parting blades. Sam
View attachment 323026View attachment 323027View attachment 323028View attachment 323029

Hi do you have any of these Armstrong blades left?
I need one (or two perhaps)
Hoping and wishing...
Thank you,
"Jake"
Canoeyawl at hotmail.com
 
I have a Williams #32 "Agrippa" cut-off holder, takes 7/8" blades- its a great toolholder. If you have some that size I'd love to get two- I don't mind the make. The tool has single much-hacked up Williams blade in it.
 








 
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