First lathe, tool bits

My thought is that smaller HSS bits are less time consuming to grind and less expensive to purchase. Maybe you could start with 3/8 and move up to 1/2 later, when you have more experience with grinding. You might even start with 5/16 or 1/4 if your tool post will accommodate those sizes.

I think that grinding my own has become fun and satisfying, although I admit that I started with some pre-ground bits that came with my lathe.
 
Thanks for all the suggestions!

I would like to learn to grind my own bits. I enjoy the learning process as much as actually making stuff, its kind of in my DNA. Also, I'm pretty sure old my lathe tops out at 500rpm in the top gear with the motor at 60hz. Even if I run the motor faster than rated i'm still barely breaking into carbide speeds. I think this really limits me to HSS.

I dug out all the bits in the box of stuff I got with the lathe. Here is what I currently have to work with that came with the lathe. Most of the bits look like they were either ground for a specific profile or were broken in use. The labels I can read on them suggest that some of them branded REX.

The majority of the bits are 3/4" or 1/2". The tool holder I have can hold up to 3/4 bits.

Most of the 1/2" bits are generally between 1.5" and 2" long as is. The 3/4" bits are similar lengths as you can see. I'm not sure what the usable length of the bits needs to be, but to be held by 2 set screws on the tool holder they need to be at least 1" long plus whatever stick out amount is needed. I would think that leaves me very little wiggle room on regrinding the profiles.

I have close up pictures of each size of bit if it helps.

allbitslabeled.png
 
I love looking at old tool bits. Some of them have some really esoteric shapes and I wonder what the guy was thinking when he ground it. I have seen some bits that were ground by a skilled machinist, complete with cleanly formed shapes and angles, but such is not the case here, Jmanb. Don't mean to seem snobby or anything but I honestly don't see anything in the pic that I would choose to reproduce.

If it were me, I would start from scratch. I would buy some cheap Chinese 1/2" HSS tool bits from ebay and while I'm waiting for them to arrive, I would go to the hardware store and buy some 1/2" square keystock. I would cut the keystock into bit-sized pieces and learn to grind tool bits on that; it grinds easily and is cheap. It will also take light cuts, although the edge won't hold up for too long.

There is a lot of info on tool grinding on the net and this site - search, ask questions and someone will help guide you. On a big 15" lathe, you are less worried about cutting forces, power or rigidity than some of us with smaller lathes so the angles in the typical lathe tool angle table will work fine for you. As for shapes, intjonmiller illustrated the shapes that were typically used on older machines with older style tool posts and they work fine. Nowadays, with the QCTP, we can also use a more generalized shape that works for most cuts we make. Again, search because I don't want to bog down your thread with too much detail here.

I would also agree with you that if your lathe can only run at very low speeds then HSS or possibly brazed carbide might be your best bet. Regardless of which you use, I agree with Willthedancer and would hone the cutting edges with a stone, either synthetic or diamond.
 
Everybody has an opinion, it reminds me of the Ford/Chevy/mopar discussions.

If you want to go carbide, I would stay away from this type of brazed on carbide:
s-l500.jpg


I am no expert by any stretch of the word! But I find that I can do very well with HSS hand ground bits and then tried some of the cheap brazed carbide ones similar to the photo from HF. I wasn't happy at all with how they cut and the finish they produced. You can dress them with diamond sharpening stones to make them a little better. Then I found some NOS carbide insert tooling and tried it. The difference between the insert carbide and the brazed carbide is like night and day. Several name brand HSS tooling was already mentioned, try to find some of those rather than eBay ones of mystery HSS.
Just my .02

Jnamb13, shoot me your name and address in a pm, I think I have a new old stock HSS MoMax in 3/8" i can drop in an envelop to you, if you'd like to try grinding your own.

Mike
 
Brazed carbide tools are just fine if you get good quality ones, and grind them properly as they need it. You can make them sharper than how most inserts come, which cuts nicely, leaves a good finish, but also needs grinding more often. Depending on the grade and quality, they can be very good for interrupted cuts as well. I have had some luck with grinding cheap Asian brazed carbide tools to a form that actually might cut something and getting good work out of them. Others have been poor in just about every respect.
 
Bob Korves said:
Brazed carbide tools are just fine if you get good quality ones, and grind them properly as they need it. You can make them sharper than how most inserts come, which cuts nicely, leaves a good finish, but also needs grinding more often. Depending on the grade and quality, they can be very good for interrupted cuts as well. I have had some luck with grinding cheap Asian brazed carbide tools to a form that actually might cut something and getting good work out of them. Others have been poor in just about every respect.
Click to expand...

Bob,

can you explain what a "good quality" brazed carbide tool is? Brand? Price seems a crap shoot. I know not to expect too much from HF, what about buying on eBay? What is there to look for?
 
I'll let Bob give you the real answer but I like and use Micro 100 brazed carbide tools on occasion. In my opinion, they are the best of their kind.
 
Reeltor said:
Bob,
can you explain what a "good quality" brazed carbide tool is? Brand? Price seems a crap shoot. I know not to expect too much from HF, what about buying on eBay? What is there to look for?
Click to expand...
I went out in the shop and dug into the top layer of the brazed carbide. Lots of Kennametal, Carboloy, Morse, Firthite, and Lake. Also some Armstrong, Super Tool, and Modco, and some unbranded. To make it simple, all the brand names ended in USA, and the majority of these tools might be older than half the people on this forum, from back when these tools were what was used in production and job shops, before inserts took ahold. Nearly all are new, unused, in beautiful condition after some Evapo-Rust, some elbow grease and some ATF. I have at least a hundred of them, 1/4" to 3/4", 20 pounds or more, in various configurations, and not more than $10-15 cost in the whole stack, Craigslist tool lot purchases. They work really well. Don't pay retail! Try not to buy junk!
 
Since I want to get started quickly I ended up picking up a lot of vintage bits off ebay. Its a combination of Mo-Max, Firth, and Empire bits. Not the "best" price. But at around $1.30 per bit it sure beats the $15+ per bit that MSC wants for new 1/2 USA bits.

I'll be keeping a lookout for really good deals in the future, but I wanted to get started ASAP, and this auction seemed to be a decent enough deal for what was there.

http://www.ebay.com/itm/30-Vntg-HS-...gKfUL0TRpk7CkVVYQ%2B8%3D&orig_cvip=true&rt=nc
 
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