How to make a cut off tool?

True wreck, but at the same time, as little as I'd use it, I'd only have to make it once. The hack saw trick sounds easiest, or buying one. But, if I have the tooling stock and the free time, it doesn't cost me anything and experience is most often a good thing. Your thoughts?

Wayne
 
A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.
Img_1921.jpg


I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.
Img_7597_zpscb8b5dd7.jpg


Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544
 
Yep, that's my tool lantern, your holder is different than mine, mine only hold square tools, I do have one holder that is angled in like yours there but it also only holds square tooling stock. I didn't recall a cut off being that thin, It seems to me we were shown how to grind one out of square stock in school, but I don't remember if we actually did it or not. If this is too much trouble, I just cut a v and hack saw it or do it the way I have been but I like that, I only wish I had a tool holder like that. Not much point in buying a holder and tool for something I use so rarely. If I can make one out of square tool stock, I would be willing to do so, if someone has the dimensions. Or at least a picture, I could then decide if I want to bother.

Wayne
 
A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.
Img_1921.jpg


I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.
Img_7597_zpscb8b5dd7.jpg


Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

i-v3x8TcR.jpg

i-x2GPFMd.jpg

i-zF9GNDW.jpg
 
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Wayne, you can grind the parting tool to any thickness you wish. Just grind a couple degrees of relief on the sides and a chip breaker on top and you're good to go. You can search the Internet for a pic of a hss parting tool.
 
Also, if you don't want to go the parting blade route, you can always grind a regular tool bit into a parting tool. Just grind a notch in the corner until you get a long, narrow tongue sticking out, length and width depending on your requirements. Add clearance on both sides and the end, grind in some top rake and a chip breaker, and you're good to go.

Say for example you're working with a 1/2" square tool bit. Grind a square notch 3/8"-7/16" wide and 1/2"-3/4" long out of the front right corner. That will leave you a 1/16"-1/8" wide, 1/2"-3/4" long, and 1/2" tall cutting tip. Grind about 5-10 degrees relief on both sides, 8-10 degrees top rake, and give it a try. It's a tedious exercise; softer grades of grinding wheels will cut faster on tool steel. I like the white Norton wheels.
 
jaded13640 said:
I had to do a little project recently where I needed to make a "bushing" that was about .300 dia by about .300 thick. I had a much longer piece of steel stock, about 3 or 4 inches long, I could have cut a smaller piece on the abrasive cut off saw but, it was kind of a short piece and decided not to. But, of course that meant I had to face away ALL the stock I didn't need AND, had to hold that little tiny piece, that was the finished product, in the chuck.

So, it took forever and was just a stupid little piece to tighten up the shifter rod on a truck where the plastic bushing had worn down to nothing. It was held on with a cotter pin and it broke, I was doing a whole different project on the truck when he mentioned he had to tied it back together with a jump rope. I didn't even notice it till he mentioned it and it had no way of getting the correct bushing that late at night but HAD to get the truck done that night, he had to drive it to work the next day.

What might have done better?

I took the entire machine tool operations sequence in college to get my drafting and design degree years ago. The idea was that by having to actually make stuff we'd become better designers because we'd understand things like tolerances. For example, why you don't put a four place decimal on a drilled clearance hole, you really can't achieve that kind of accuracy with a drill. It all made sense than AND I learned I was actually pretty good at machining in the process. At one point when I got laid off from one design shop I worked as a machinist at a shop. It was great to have gotten that training that I never guessed I'd need. Now I have a small mill and lathe if I need to make something.

So how could I have made that simpler? What should I have done to cut the time? I don't have a good way of cutting stock, the only way I could have really done it better with what I have is to have put the stock in the vice and cut it off with a cut off wheel/die grinder.

Maybe I could have turned the diameter and then used a cut off tool, but I don't know how to make one, I can't remember how we did that in school and never had to do it in the field.

Thanks in advance,

Wayne
Click to expand...

Wayne, you can buy parting tools in a T configuration. The T is made so all you have to do is grind the front relief.
The sides are narrower than then the top so no extra grinding necessary. These tools come in different thicknesses.
I have 3 thicknesses , 5/64" , 1/16" , and 5/32". You can make a holder that fits your tool post. Slot a piece of stock that allows the parting tool to slip in, then hold it tight with several set screws drilled and tapped into one side. Might be possible to eliminate the slot, just drill and tap a piece of square stock that will push against the T tool. The T sits tight against the back of the lantern and the square stock is held in the lantern and set screws push against the T.
mike
You could also use high speed steel blank cutter and grind it to the proper width . This takes a long time and proper relief must be ground on the front, sides and top. Much easier to buy a T type of tool.
 
I liked both of your comments. I like the ideas both presented. I do so little on that lathe, I can't see going to too much trouble. I remember learning about parting tools but I don't remember being taught how to use one or actually seeing one back in college. I can only assume that's why I seem so in the dark about this. It turns out, it seems, that it's more trouble than it's worth. It's looking like, in my case anyway, it would be way easier to be wasteful, leave it long and just machine more away than going to all the effort to make a tool, or the expense to buy a tool. When I realized what was really involved, I realized it probably wasn't going to be worth it when I only roll the machine out and do something with it once or twice, three at the most times a year. Many of those times a cut off tool wouldn't even be needed. It's looking like it would be easier for me to cut my stock off, leave a little long and just clean it up face it to size. That just seems like the smartest way for MY situation. It would be different if I were using it once a week and wasting a bunch of stock. I've only actually had to buy any stock a couple of times, I've just gathered pieces of scrap here and there which is mostly all I need.
 
OK...Lets talk about single point threading....LOL
 
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