Plunge grinding

skipd1 · Nov 3, 2017

I have a Harig 6x12 and I am dry grinding a 1/4" channel into a 12" length of 3/4 inch 1045 ground rod. I have been taking about .00015 steps down and it seems that is about all the grinder and myself want to go. Seems that there is plenty of heat so I am going slow to final depth of about .0050 total. I am using a 6x1/4 inch Norton 46H wheel. Comments Please.
Thanks

Skipd1

Milland · Nov 3, 2017

skipd1 said:
I have a Harig 6x12 and I am dry grinding a 1/4" channel into a 12" length of 3/4 inch 1045 ground rod. I have been taking about .00015 steps down and it seems that is about all the grinder and myself want to go. Seems that there is plenty of heat so I am going slow to final depth of about .0050 total. I am using a 6x1/4 inch Norton 46H wheel. Comments Please.
Thanks

Skipd1

If you can mill the slot either to size, or slightly under and finish grind it will be a lot faster. If the rod is case hardened there's endmills good to RC70 that will cut through it: 1/4" 4 Fl Stub 3 Deg Helix Corner Rad Ext Neck X5 Blue Coated Nanograin Carbide End Mill

More information on surface finish and accuracy requirements will help with advice.

BSCustoms · Nov 3, 2017

I might have tried a 46J just because that is usually what is set up and dressed. I would not hesitate to take .0005 passes between traverses.

is this hard material? can you get a mister going? and you only need 5 thou depth?

cash · Nov 4, 2017

When plunging a channel your heat from grinding is always concentrated on the same area. Heat will ALWAYS be an issue. I always generate heat if I wet grind and plunge.

Can you get a spray bottle with come coolant/lube to help the situation out?

Make sure you are using a free cutting wheel. I assume your 46H is a white wheel? Like a 38A which is a friable grain.

SeaMoss · Nov 4, 2017

skipd1 said:
I am using a 6x1/4 inch Norton 46H wheel. Comments Please.

Change to Cubitron II or whatever Norton calls theirs and turn on the coolant. And ask Michigan Buck, who's got his grinding shit down.

Borazon would eat that up too, but expensive

Toms Wheels · Nov 4, 2017

I would narrow the wheel .050, and use mist coolant. Alot of extra heat from rubbing of the sides without cutting, This way only rubs on one side, and no pinching from both sides.

Oh, is that .005" depth. just use mist. On round stock there is little heat transferred to the chuck, so for sure use mist or chilled air.

skipd1 · Nov 4, 2017

Yes it is a white wheel and thanks for the spray bottle idea. My shop is just for hobby so no coolant or mister. What kind of coolant should I use in the spray bottle for this material?

skipd1 · Nov 4, 2017

Thanks everyone for the great response.

Skipd1

cash · Nov 4, 2017

Do you have other mills or lathes that have coolant? Anything will work.

If you have nothing around mix some mineral spirits and water???

tdmidget · Nov 5, 2017

cash said:
Do you have other mills or lathes that have coolant? Anything will work.

If you have nothing around mix some mineral spirits and water???

How does one mix mineral spirits and water? Without an emulsifying agent such as dish soap ( Dawn), it ain't gonna happen, and then will depend on your ability to homogenize it.

cash · Nov 5, 2017

tdmidget said:
How does one mix mineral spirits and water? Without an emulsifying agent such as dish soap ( Dawn), it ain't gonna happen, and then will depend on your ability to homogenize it.

yea.... I know- but what does one do in a shop if they have no coolant???

light mixture of engine coolant and water???

tdmidget · Nov 5, 2017

Hmm, anitifreeze is quite toxic. a mixture of water and a little dish soap would have a low surface tension but even with coolant this thing may go banana shaped especially if heat treated. Instead of plunge grinding how about mill it and finish grind?

rogertoolmaker · Dec 23, 2017

Grinding wheel selection

skipd1 said:
I have a Harig 6x12 and I am dry grinding a 1/4" channel into a 12" length of 3/4 inch 1045 ground rod. I have been taking about .00015 steps down and it seems that is about all the grinder and myself want to go. Seems that there is plenty of heat so I am going slow to final depth of about .0050 total. I am using a 6x1/4 inch Norton 46H wheel. Comments Please.
Thanks

Skipd1

You might try a Norton 38A80I8VBE full dia. wheel. A 46H wheel will break down faster. I would want to mill out the slot and then grind to get rid of the material. It should run cooler due to the smaller stone size.

Roger

stephen thomas · Dec 23, 2017

(engine) antifreeze mist is bad for you, as has been mentioned.

Get a gallon of something like Trim Mist. It's not exactly cheap but can be thinned down to less than 30:1 (1 gal make 31 gals).
Around 25:1 will give pretty good rust protection on your tools and machine without much extra care, drying, etc. Another one I like on the bigger grinder is Cinncinati "Cimcool 95" but that might not be available in less than 5 gal pails.

Some sort of ad hoc water base shop mix will work fine for grinding but you better be scrupulous about= clean, dry, oil every surface, part, and tool you put away in the cabinet.

If you plan to keep using a grinder, get a cheap mist gun. They work pretty well.

smt

tdmidget · Dec 23, 2017

rogertoolmaker said:
You might try a Norton 38A80I8VBE full dia. wheel. A 46H wheel will break down faster. I would want to mill out the slot and then grind to get rid of the material. It should run cooler due to the smaller stone size.

Roger

That is ridiculous. The 80 grit will produce at least twice the heat of the 46. The op has only one thing going for him and that is the .005" depth. Can it be ground? Of course, but the rough mill and finish grind is at least twice as likely to be successful at normal grinding tolerances.

AD Design · Dec 24, 2017

This may not apply but I'll throw it out there. Often there would be an engineering change to a die section, sometimes dictating that a rail lifter be put in that would require a slot in hardened A-2/D-2. Milling is my first choice also but that isn't always possible if you're without carbide end mills. I have, with good results, used a cut off wheel in the SG to make several slots in the proposed area while using a spray bottle to control heat. If the depth of the slot is greater than 4x the width of the remaining "rib" it can be simply broken off with a brass drift. If not, you've removed a lot of material that you don't have to grind and reduced heat/wheel wear. This method is especially effective with large amounts of hardened metal like D-2 or the powdered metals that are abrasion resistant. Yes it's two set-ups and two wheel changes but it's a fairly quick method and only requires leaving enough material on the bottom/sides for cleaning up the gash. It doesn't matter how the excess is removed, only the last bit of it. More gashing for thinner "ribs" makes breaking them off fairly easy. Hope this helps someone.

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