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How to properly make blocks

Avsfan135

Cast Iron
Joined
Jan 19, 2011
Location
Fort Collins, Colorado
Forgive me please I posted this in abrasive machine then here because I was hoping for more views here!!


I have a Harig surface grinder at work. (pics to follow) We just got it hooked up coolant tank cleaned a new diamond dresser.

I am trying to learn grinding (totally green!) we really have no use for the grinder at work but it's just sitting there so we got it wired.

I tried to make some blocks 1.25x1.5x2.0 out of 17-4

I got really close on the 1.250 dim. I got 1.2501-1.2502 but I overshot the 1.5 by a few tenths.

What I want to do is make some blocks out of something I can harden. We have 4140hf annealed 4130q&t

Now for the questions!!

What should I make the blocks out of?

How big should I make them before hardening?

Does it shrink or grow at all?

Is a rough cut on the mill ok or should I grind before hardening?

What is the best way to ensure squareness? Flatness and size I understand but squareness I'm lost in how to controll or adjust for that.

I guess that's all for now


Any and all suggestions or comments are very welcome!

Thanks
Nick
 
Forgive me please I posted this in abrasive machine then here because I was hoping for more views here!!
I'll try to help.


I have a Harig surface grinder at work. (pics to follow) We just got it hooked up coolant tank cleaned a new diamond dresser.

I am trying to learn grinding (totally green!) we really have no use for the grinder at work but it's just sitting there so we got it wired.
A grinding machine is very dangerous. You don't just plug it in and go trial and error. If you have someone in your shop who knows something about grinding, learn from him. Trouble every shop has a guy who claims to know all about grinding. He does not easily share this information, usually because he does not really know shit. If you suspect that that is the case, at least ask here.

I tried to make some blocks 1.25x1.5x2.0 out of 17-4

I got really close on the 1.250 dim. I got 1.2501-1.2502 but I overshot the 1.5 by a few tenths.
It'll happen again, this is how you learn. You make home projects like this so you don't learn how expensive your customers parts are by screwing them up.

What I want to do is make some blocks out of something I can harden. We have 4140hf annealed 4130q&t

Now for the questions!!

What should I make the blocks out of?
17-4 is fine. You can easily harden it to 44-45 rC (air hardening), hard to mess up with this.

How big should I make them before hardening?
At least .010 over. More if you machines are not capable of getting close enough.

Does it shrink or grow at all?
yes but doesn't matter. you are grinding after heat treatment.

Is a rough cut on the mill ok or should I grind before hardening?
Mill it .010 over. Keep it as square as you can.

What is the best way to ensure squareness? Flatness and size I understand but squareness I'm lost in how to controll or adjust for that.
You will need a squaring block. You can square some surfaces against the back rail but you will need the block for all 3. It is a very precise angle block with a step to hold the part square. You can do it with a regular angle block but it is a lot of work to get it square and clamped that way.

I guess that's all for now
You will have plenty more questions, don't be afraid to ask.


Any and all suggestions or comments are very welcome!
WORK SAFE!!!!

Thanks
Nick
be careful!
 
Now for the questions!!

What should I make the blocks out of?

How big should I make them before hardening?

a lot depends on the material and part shape- but for your example (a square block), I'd make it out of whatever is handy and will harden, and leave .005-.01 per face

Does it shrink or grow at all?

to make a square block, doesn't matter: I.E. if it grows, you'll be grinding anyways, if it shrinks, the .005-.01 you left on for grinding will still give you material to remove.

Is a rough cut on the mill ok or should I grind before hardening?

rough cut is fine

What is the best way to ensure squareness? Flatness and size I understand but squareness I'm lost in how to controll or adjust for that.

you need some kind of 'known' square to compare against, and an indicator, if you want it perfectly square. If you are okay with it being withing a few tenths of square +/-, set it up in a toolmakers screwless vise, grind one side, flip the vise on it's side and grind a second side without removing the block from the vise between ops.


Thanks
Nick

hope this will get you off and running, grinding is a handy skill to have, and access to a grinder is a must if you want precision. It's and absolute neccessity if you need to make tools for yourself or the shop.
good luck!:cheers:
 
I often clamp bits to my 123 blocks to get square set-ups. A stack of thin tissue - aluminium foil as shims is great for finer adjustments. My problem is i want to start grinding angles and that means making a sine plate type set-up, not cheep as i need another magnetic chuck to do some of the bits i want to do :-(

Don't forget not all heat treatable steels are that magnetic, especially smaller bits hence always make sure the magnets got them don't just assume it has!
 
Leave a few thou. oversize before you harden the blocks. You can use tool steel or just something you can case harden. They will move when heated so then you can trim them up on the grinder to final size and squareness. You can use the same mill techniques for squaring if you have a good vice, otherwise transfer blocks and packing to get started.
 
What is the best way to ensure squareness? Flatness and size I understand but squareness I'm lost in how to controll or adjust for that.


Thanks
Nick

To make a 1-2-3 type of block that is hardened and then precision ground is a very advanced project. A whole book could be written on how to do it. (maybe there is one?)

A 1-2-3 block sounds so simple, but to hit your numbers and have six sides that are perfectly square to each other isn't something that can be covered very well in a forum post. Hopefully one of the other members here can recommend some books.
 
AND though you may have missed it in the posting guidelines, you ARE required to tell how the next attempt turns out.:D
 
You've asked enough of the right questions that I'm sure you'll get this.
One thing I will add...use a good fine India stone to clean your chuck and parts while setting up. Did I say clean?...I meant really clean. Can make an average toolmaker into a good toolmaker.


.....

What should I make the blocks out of?
O-1..double draw (temper) or any of the air hardening steels. Cryo treatment is all the better.
edit: Reread your question...4140 would yield more hardness which you can still double draw


How big should I make them before hardening?
+.005"/side is the norm

Does it shrink or grow at all?
It will grow, not much. Usually only need to compensate for feature locations on parts greater than 6" length. (google martensite and austenite for the reasons why)

Is a rough cut on the mill ok or should I grind before hardening?
Rough cut OK

What is the best way to ensure squareness? Flatness and size I understand but squareness I'm lost in how to controll or adjust for that.
GOOD grinding vise...GOOD squaring block and toe clamps...and double check on surface plate with known square w/indicator.

I guess that's all for now


Any and all suggestions or comments are very welcome!

Tha0nks
Nick
 
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You also may need to get your machine & setup square before you start to grind. This means you might have to grind the chuck and fences to get them square as well as anything you are clamping to. Try plenty of test pieces first. I'm sure grinding the table has been well covered in these forum before.
 








 
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