Need Help!- Ask me anything about machining

[mirobbins]

I am new on this web site. Let us see if I can help. Ask me anything about machining.

[spoiledbrat]

When grinding a custom lathe tool from HSS, is it bad to cool it using ice water?

Also, what is the color of the material when I have heated it too much? (Am I allowed to see a light amber color?)

Cheers!

Rob

[mirobbins]

Dear Mr Brat
It doesn't matter if your water is warm, cold or Ice cold. If your grinding a custom lathe tool on a pedestal grinder your fingers are going to get pretty warm when the tool starts to turn an amber color. You will probably drop it pretty quick. I have ground many tools by hand and as you rough the stock off to get your shape you will heat portions of the tool to a glowing red. The hardness of the tool will soften on the surface and you will need to cool the tool before you grind the finished size and surfaces. The finish grinds will remove the softer material exposing the harden edge. It is a good practice to keep your tool as cool as possible to insure a good cutting edge. ( Move on to Carbibe and sharpen the tool on a surface grinder)

[MrWild]

How much does A2 steel grow during heat treat? When machining a form die from soft A2, what scale factor needs to be used so that after heat treat the die steel is to size?

[mirobbins]

You got me Mr Wild. Off the top of my head I do not know and since I do not have my Machinery Handbook handy I a cannot answer that specific question at this time. But I can tell you that A2 has a very low distortion rate and is very shock resistant. That is why the material is used for punches. (M2 for the die section for its wear characteristics) After heat treating A2 the surface will still have a thin layer that is soft .002-.004 deep so I do not think you want to machine your form die to size and then heat treat and not grind or machine to size the surface you will be using for the forming operation. With todays cutters and CNC machine tools you can very easily machine the forming surface with a ball endmill and finish by polishing with emery or diamond compounds. All square and flat surfaces I would surface grind after heat treat.

[cob]

my turn can you tell me what I can do to take the rust off some stell tools I left outside for about a year. and where can I get it

[praveenkusuma]

Can anybody suggest how to calculate the cutting force for a rough end milling operation?
It would be helpful if anybody can mention the formulae (in metric units) to calculate the correct cutting force for rough end mill operations.

Praveen

[Kipper]

How do I get an engineer of 32 years to drill holes in the right place and not blame the centre punch?

fyi beating with a stick has been banned for some time here!

[mirobbins]

Dear Mr Cob, you can us WD30 to remove the rust and you can purchase it at any hardware or autoparts store. If the rust is deep you may want to consider using glass bead or crushed walnut shells and blast the surface clean. If we are talking about hand tools and wrenches than you can use fine sand blast material. (Try putting your tools away when your done and save yourself some extra work)

[mirobbins]

Dear Mr Preveen Cutting force caculation require more information than you have provided. Are you cutting plastic, mild steel, tool steel, stainless steel or aerospace alloys? If you have access to a Machinery Handbook you will find all the formulas you will ever need.

[mirobbins]

Dear Mr Kipper, I do not think you have an engineer problem, it sounds more like a management problem. (Look in the mirror) Try giving the job to a skilled machinist instead of an engineer.

[HuFlungDung]

mirobbins,
Does one need to be a welder or have any skills to run a UTP metallizing rig, or is it so simple that anyone who can run a lathe can do it?