A grinder for HSS toolbits

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Harold_V
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Re: A grinder for HSS toolbits

Post by Harold_V » Mon Aug 02, 2010 2:50 pm

Oh, yeah! That looks killer good! By the time you've worn a 7" wheel down to 5½", it won't be up to much unless you can speed it up.

I think you're going to be well pleased with the setup.

Harold

EdK
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Re: A grinder for HSS toolbits

Post by EdK » Mon Nov 15, 2010 7:54 pm

If you're looking for some grinding wheels for your HSS grinder per Harold's thread, MSC has some made in the USA wheels on sale for $14. Their regular price is $21. They are on page 21 of their current metalworking "Best Choice" sales catalog.

http://metalworking.mscdirect.com/conte ... ndex.shtml

Ed
Vectrax 14x40 lathe, Enco RF-45 clone mill, MillerMatic 180 MIG.

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SteveM
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Re: A grinder for HSS toolbits

Post by SteveM » Tue Nov 16, 2010 8:20 am

Harold_V wrote:By the time you've worn a 7" wheel down to 5½", it won't be up to much unless you can speed it up.
When your wheel gets down to 5-1/2", send it to me. My grinder is only 6" and wheels are harder to find and more expensive.

Steve

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ken572
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Re: A grinder for HSS toolbits

Post by ken572 » Wed Dec 01, 2010 10:51 pm

Harold,

Thank You once again for this fantastic treatise., and great read. :wink:

Ken. :)
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

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Benesesso
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Re: A grinder for HSS toolbits

Post by Benesesso » Fri Mar 25, 2011 11:09 am

Realizing I needed to buy some 7" grinding wheels ala Harold (38A, soft, 1.25" center hole), I found some on eBone. Got 2 ea. 46 grit, but 1/4" wide instead of 1/2", H bond strength. Also got 2 80 grit wheels in 1/2" wide, softer G bond.

Then I bought an 8" HF grinder, and a nearly rust-free 36" length of 2.25" round steel at my favorite metal scrapyard, for $20. I know 2.25" isn't 2.75", but it'll have to do.

Next, I made a crude drawing of the wheel adapters needed (attached as a .pdf). The HF grinder shafts have a step ~.020" (~.040" on the diameter) which is the flange/adapter stop/shoulder. I figured I'd add .001" for clearance, and that's what's on the drawing.

Now I need some experienced help on how to make these things on my 12" Clausing lathe. I have a nice Johnson J horizontal bandsaw to cut the long shaft to size, so how long a piece should I cut off? Also, what machining sequence makes sense for these (I'll make 2 of course).

I have a nice small boring bar, with a carbide tip--came with the lathe.

My first lathe project in ~53 years!
Attachments
DOC032511.pdf
7" X 1.25" Hole-Grinding Wheel adapter for HF 8" Grinders
(132.53 KiB) Downloaded 406 times
Gold is for the mistress - silver for the maid
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall
But iron - cold iron is the master of them all.
Rudyard Kipling

Harold_V
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Re: A grinder for HSS toolbits

Post by Harold_V » Fri Mar 25, 2011 2:41 pm

Benesesso wrote: how long a piece should I cut off? Also, what machining sequence makes sense for these (I'll make 2 of course).
It's not clear to me if you are going to make just flanges, or adapters that fit the shaft of the grinder. I expect it's the second choice.

Before you start the project, think about how you'll machine the second side. It's important that you be able to locate the adapters such that they are concentric and perpendicular to the machining of the first side, to limit vibrations and to insure the wheels run true.

Good machining practice dictates that parts should be roughed fully before finish cuts are taken. I'd advise that for these pieces as well. If you do so, cut the stock slightly longer than the finished dimension. Rule of thumb is to allow 1/16" for each face, which addresses the fact that saw cuts are often not at a right angle, so you must allow for blade wander.

Having the ability to use soft jaws can go a long ways towards making it easy to make these parts. If they are not at your disposal, a four jaw and a DTI is likely the next best choice.

Those ¼" wide wheels can be to your advantage if you're grinding tools for shallow internal work.

Do use caution with the thin wheels, especially with the reduced diameter of the material you intend to use. The wheels likely will not tolerate much side pressure without fracturing. Wider flanges (larger in diameter) lend more support.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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Benesesso
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Re: A grinder for HSS toolbits

Post by Benesesso » Fri Mar 25, 2011 3:24 pm

Thanks, Harold.

My thought was to make only the inner adapter/flange, which will carry and locate the wheel both radially and axially. The original HF stamped outer flanges are 2" dia, so there won't be any bending moments on the wheels. The motor takes its time coming up to speed, so I don't see the need to tighten the shaft nut all that tight.

The orig. outer flange will merely press the wheel against these new adapters, so I don't see any reason to make anything for the outer flanges.

Because the adapter is only .87" long, I'm thinking I should start with a piece ~1.5" and turn the .864" dia. first. Then drill/bore the .623" thru hole, bore the .664" end, then turn it around and machine the rest of it.

My lathe has a good 8" 4 jaw chuck but no DRO, so I'll be taking a lot of measurements.
Gold is for the mistress - silver for the maid
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall
But iron - cold iron is the master of them all.
Rudyard Kipling

Harold_V
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Re: A grinder for HSS toolbits

Post by Harold_V » Fri Mar 25, 2011 11:56 pm

Benesesso wrote:My thought was to make only the inner adapter/flange, which will carry and locate the wheel both radially and axially.
That makes sense, assuming the motor shaft has a decent shoulder for the assembly against which to bear. If you have any doubts, might not hurt to make a slight cut to insure it's square. You'd have to dismantle the motor, but that's usually not much of an ordeal.
The original HF stamped outer flanges are 2" dia, so there won't be any bending moments on the wheels.
That's good, but my main concern is in use. In spite of what you read, you do use the side of a wheel, and more often than you might imagine. Just don't horse the grind when you find you must. My thoughts are that the larger flanges would not only provide support closer to the perimeter, but a greater percentage of the wheel would lend support. I'm looking at this from a safety standpoint, not suggesting that it won't work.
The motor takes its time coming up to speed, so I don't see the need to tighten the shaft nut all that tight.
That's actually good practice. Wheels should never be tightened excessively. The most force I use is to hold the wheel with a bare hand and tighten the nut with a wrench. That's more than adequate unless you're doing some very heavy grinding---which is most unlikely to occur on a dedicated tool grinder.
The orig. outer flange will merely press the wheel against these new adapters, so I don't see any reason to make anything for the outer flanges.
I'd consider doing so if you find the bearing portion isn't dead flat. It's quite desirable to clamp wheels over a broad area. Also, insure that you have a blotter on both faces.
Because the adapter is only .87" long, I'm thinking I should start with a piece ~1.5" and turn the .864" dia. first. Then drill/bore the .623" thru hole, bore the .664" end, then turn it around and machine the rest of it.
Without seeing a sketch of the adapter, I'm not sure I follow the dimensions, although the .623" bore makes sense. The .664" dimension leaves me wondering----and I'm not convinced you should make the turn .864" diameter. Unless there's something I don't understand, I'd suggest that you shoot for common fraction size, so if you have to hold the piece in a collet for any reason, you're more likely to have a collet on hand. .864" is clearly a bastard size. As for the length of stock---again, unless there's something I don't understand, you can make it from a piece that's 1" long, or you can use a piece that's 2" long and make one on each end, then split them.
My lathe has a good 8" 4 jaw chuck but no DRO, so I'll be taking a lot of measurements.
I'll let you in on a little secret.

I started in the shop (commercially) back in '57. I've spent years on machines---and I've never in my life relied on a DRO. In fact, I've never operated a machine so equipped (discounting my CNC mill, of course). You can do amazing close tolerance work without a DRO---a fact proven by the US winning World War II, all without DRO's and/or NC or CNC equipment. It sorts those that think they can from those that can.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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Benesesso
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Re: A grinder for HSS toolbits

Post by Benesesso » Sat Mar 26, 2011 8:21 pm

Harold_V wrote:
Because the adapter is only .87" long, I'm thinking I should start with a piece ~1.5" and turn the .864" dia. first. Then drill/bore the .623" thru hole, bore the .664" end, then turn it around and machine the rest of it.
Without seeing a sketch of the adapter, I'm not sure I follow the dimensions, although the .623" bore makes sense. The .664" dimension leaves me wondering----and I'm not convinced you should make the turn .864" diameter. Unless there's something I don't understand, I'd suggest that you shoot for common fraction size, so if you have to hold the piece in a collet for any reason, you're more likely to have a collet on hand. .864" is clearly a bastard size. As for the length of stock---again, unless there's something I don't understand, you can make it from a piece that's 1" long, or you can use a piece that's 2" long and make one on each end, then split them. Harold
I attached a sketch in the first message. Most of the motor shaft is .622" dia., thus the reason for the .623" hole. The stepped-up dia. is .663", so I thought I'd make the hole ~.001" bigger--therefore the .664" dia.

I can make the OD .875" instead of .864". The .864" came from thinking I'd make the wall thickness .10"--now it will be .1055" instead.

What's the preferred method for turning the 2.25" stock OD down to .875"? Should I take a lot of light cuts with a higher longitudinal feed rate, or take heavier cuts at slow feed? What's a good amount to remove in one pass?

The slowest RPM my lathe goes is 360 RPM without engaging the backgears, so I'll probably be using backgear for most of the work. Good thing I'm retired and have lots of idle time.
Gold is for the mistress - silver for the maid
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall
But iron - cold iron is the master of them all.
Rudyard Kipling

Harold_V
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Re: A grinder for HSS toolbits

Post by Harold_V » Sun Mar 27, 2011 12:48 am

Benesesso wrote:I attached a sketch in the first message.
:oops: :oops:

Yes, it appears you did! :-)
What's the preferred method for turning the 2.25" stock OD down to .875"? Should I take a lot of light cuts with a higher longitudinal feed rate, or take heavier cuts at slow feed? What's a good amount to remove in one pass?
A great deal depends on the tooling you have at your disposal. If that was my project, I'd rough with negative rake carbide, taking .400" off the diameter per pass. You can get the material off in a minute or so.

If you don't have insert carbide, negative rake, you can take the cut with a right hand HSS turning tool with a decent chip breaker, and take the same amount off per pass, but it would be at a much slower speed. I don't recommend you try that at this point in time, however. You should get familiar with your lathe and get a feel for its capabilities. A cut of that depth may (or may not) be a little too much for the machine to handle well. There's no need to put yourself in a position where things can go wrong.

When roughing, depth of cut and feed rate is how you get rid of material. I tend to discourage repetitive shallow cuts, which waste time and wear out tooling prematurely. There's usually no need for a finish of any description, so you use a coarse feed and appropriate speed. Judge speed by observing acceptable surface speeds for the material you'll use, and observe the color of the chips coming off. With HSS, if they are anything beyond a hint of yellow, you're running too fast. Brush apply cutting oil, to both lubricate and cool.

Considering this will be a refresher course for you, I'd suggest you take it slow and easy. Experiment with depth of cut and feed rate. Start with a feed rate of about .010" and a depth of cut of .075" (per side) and see how it behaves. As you alluded, you'll likely need to work in back gear, both for surface speed control and torque.

If I was to make the parts, now that I've seen the print, I'd make them on a common piece of stock, roughing both ends first. I'd rough turn the .875" diameter, leaving .03" for finish cuts, then drill the hole through. Drill it 9/16" through the entire piece. Turn the material over and rough the other .875" diameter. Cool the part, then face, turn the .875" and face the flange to proper length. Bore the .623" hole slightly beyond the finish length of the adapter, then bore the counterbore. Debur, then reverse the material and repeat.

When you have both ends finished, split the two parts. The finish bored .623" diameter will permit you to dial in the part, using a four jaw chuck and shims between the part and jaws, to prevent chucking damage. Hold the part by the .875" diameter, and leave enough room between the back side of the flange and the chuck jaws so you can run a DTI against the finished face, to establish perpendicularity. You'll chase the part a little, for as you tap it to get it perpendicular, you'll lose the concentricity. Work both features until they run true, then rough and finish the 1.249" diameter to proper length. Debur. Done. Don't be afraid to use a little abrasive strip to polish the turns if you don't like the finish, or if you're near size and want to bring size in. You can easily polish a half thou, and it can be difficult to take so little off when machining steel. It likes to tear and not cooperate.

Do NOT use a caliper (vernier, dial or digital) for your measurements. That's sure to get you in trouble*. Use a telescoping gage for the two internal diameters.

*There's no end to people thinking that a caliper is up to the task, but it clearly is not. Regardless of it's ability to read to tenths (some do), they generally don't reflect true size. When you're working with a thou clearance, it's most likely you'll miss the dimension when measuring internal diameters.

Hope this helps.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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ken572
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Re: A grinder for HSS toolbits

Post by ken572 » Sat Apr 09, 2011 9:44 pm

Harold,

I found some old books that could be helpful to all interested
in your fantastic post you have created here.
I had to share these.. :D

(Out of Copyright) Legal – Free .pdf Ebook Downloads.
(Fantastic Reads) (Early 1900’s)
Grinding Machines and How To Methods.
Go here,
http://www.archive.org/details/grinding ... 00shawrich

Then to LEFT Side View the book window.

Then Click on PDF – Then SAVE to your hard drive.

(Same procedure for these.)
http://www.archive.org/details/grinding ... 00kylirich
and
http://www.archive.org/details/grinding ... 00guesrich
and
http://www.archive.org/details/grinding ... 00guesuoft
and
http://www.archive.org/details/producti ... 00jacoiala
and
http://www.archive.org/details/crushing ... d006664mbp

Enjoy.
Ken.
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

EdK
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Re: A grinder for HSS toolbits

Post by EdK » Sun Apr 10, 2011 9:10 am

Thanks Ken. Lots of good information in those books. :)

Ed
Vectrax 14x40 lathe, Enco RF-45 clone mill, MillerMatic 180 MIG.

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