[boydage]

Chinese 3 Flute endmill 100mm 40mm doc. Carbide. Really nice. I use them new for finishing and when new they shave alloy hairs into the air leaving a finish that makes a DIY proud.

Limited to DOC of 40mm or in the case of the smaller end mills I would like to waste a small section to avoid rubbing above the flutes.

How much? 0.5mm off the diameter for 15mm or so. I've thought about putting a grinder in the vice on my lathe to do it? But is there a proper or better way?

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[mactec54]

Chinese 3 Flute endmill 100mm 40mm doc. Carbide. Really nice. I use them new for finishing and when new they shave alloy hairs into the air leaving a finish that makes a DIY proud.

Limited to DOC of 40mm or in the case of the smaller end mills I would like to waste a small section to avoid rubbing above the flutes.

How much? 0.5mm off the diameter for 15mm or so. I've thought about putting a grinder in the vice on my lathe to do it? But is there a proper or better way?

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If you only have the lathe then that's what you would have to use, normally it is done on a tool and cutter grinder, which is very simple and quick to do, there are many types of grinding machines that could be used also, you want to use a diamond wheel to grind the relief of the end mill

How much relief, will depend on the depth of cut you are using, so only grind enough to clear the depth of cut.

Cover the bed and slide ways, of the lathe when grinding.

These snips are just 2 machines that can grind anything you want on a cutter.

[boydage]

Thanks for that. Such a good endmill for $30. Doc is max 60mm the mill is good for 40mm. Interesting I've told the supplier if they put this grind into their endmills they will sell heaps but no interest.

I will start with my grinder in my lathe with a diamond wheel I will source..... Just bought a horizontal bandsaw due to arrive in the next few weeks. We need to space out our purchases to keep peace. ha

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[metalmayhem]

a bench grinder and a silicon carbide wheel is all you need to grind some relief

[mactec54]

a bench grinder and a silicon carbide wheel is all you need to grind some relief

Yes, that is how a hack would do it.

[metalmayhem]

Yes, that is how a hack would do it.

thats the way a machinist does it . It works fine for aerospace but sorry I forgot how much more advanced the hobby world is

[mactec54]

thats the way a machinist does it . It works fine for aerospace but sorry I forgot how much more advanced the hobby world is

No that's the way a hack would do it, doing it like this in any setting, can damage a high-speed spindle, as there is no way you can grind a relief round and true to the shank and cutter, by hand on a bench grinder

[metalmayhem]

No that's the way a hack would do it, doing it like this in any setting, can damage a high-speed spindle, as there is no way you can grind a relief round and true to the shank and cutter, by hand on a bench grinder

That would be to say that a weldon which is far more ground on one side would absolutely destroy a spindle . Never seen it , nor have I seen a hand ground relief destroy a spindle . I've worked in numerous shops and only one had an end mill grinder which never got used , every other one had pedestal grinders with silicone carbide wheels

We are talking about a disposable chinese end mill and I'm sure the mill it's going on will handle it

[boydage]

What if I mount the bench grinder on the saddle of my lathe? Now we talking.

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[mactec54]

What if I mount the bench grinder on the saddle of my lathe? Now we talking.

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Yes, some do it like that, but you need the grinding wheel to be on center.

[boydage]

With this mind. Only grinding DOC required and maybe 1mm or so. How much would I take off the diameter? 0.5mm? I am machining 6061. I was also wondering if I should go the other way and remove the top few mm off the flutes or stop exactly where they end. Thoughts?

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[metalmayhem]

minimal needs to come off the diameter , it's only clearance . You'll want to take a bit off the flute and you'll want to back taper the top of the flute as well , otherwise your grind may cause lines whether you grind by hand or machine

[pippin88]

You only need to take a very small amount off the diameter. The shank just needs to not rub.

Not DOC off the diameter.

I have always wondered why relieved shanks are not standard for all end mills, or at least long end mills

[metalmayhem]

I have always wondered why relieved shanks are not standard for all end mills, or at least long end mills

For the most part it's about having the right length cutter for the job . To use mactech's terms , grinding a relief is a hack , but is often enough a necessary hack . Too much unnecessary stick out from the holder only increases the risk of chatter

[boydage]

Cool thanks. Meaning DOC I was only going to go length down the endmill, as much as DOC I need to machine. Interesting I tried it out with an angle grinder installed on my lathe on a roughing bit that I did the same job too by hand on a linisher.

What it proved is no matter how careful you are you just can't get it right by hand. The endmill rotating making chirp chirp chirp sounds as I ground it round again if you know what I mean.

But with a cutting disc I got a great result.

Hey so interested why to cover my lathe when grinding? I did btw. Sparks go rusty and burn into the lathe bed?

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[metalmayhem]

Cool
Hey so interested why to cover my lathe when grinding? I did btw. Sparks go rusty and burn into the lathe bed?

carbide dust and the dust from grinding wheels are very abrasive which isn't good for your slides or any moving parts

[boydage]

This is a good subject. Because often I manufacture parts with a height of 50 - 60mm. My home built machine, well, I haven't used an endmill larger than 14mm 2 flute except for my facing bit. It's not rigid enough for anything larger.

So I either flip the part, not ideal it's an ok machine but not perfect. I would get a very small lip in the middle. Only a thou of an inch but still there.

My question then is, say 55mm DOC to finish a wall, that's quite an endmill yes? What would you use?

I actually wonder if I would get away with something like an 18mm 3 flute, new, sharp, taking off 0.2mm 55mm deep in a finish run. You have made me think about this. Thanks. Further thoughts?

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[mactec54]

This is a good subject. Because often I manufacture parts with a height of 50 - 60mm. My home built machine, well, I haven't used an endmill larger than 14mm 2 flute except for my facing bit. It's not rigid enough for anything larger.

So I either flip the part, not ideal it's an ok machine but not perfect. I would get a very small lip in the middle. Only a thou of an inch but still there.

My question then is, say 55mm DOC to finish a wall, that's quite an endmill yes? What would you use?

I actually wonder if I would get away with something like an 18mm 3 flute, new, sharp, taking off 0.2mm 55mm deep in a finish run. You have made me think about this. Thanks. Further thoughts?

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It would depend how rigid your machine is, and how good the spindle is, I have long End Mills that can do more than 100mm deep in a pass, so 55mm is not much for a rigid Machine / Spindle

[boydage]

Worked well. Although I broke the first (really cheap) endmill right at the start of the wasted section. Brittle huh.

That little lip grinder in the first pic. I've seen quite a lot of them for sale, approx US$1k out of factory. Do I look for anything in particular or are they pretty standard on the scale of things? Would be nice to sharpen even just a twist drill tbh.

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[mactec54]

Worked well. Although I broke the first (really cheap) endmill right at the start of the wasted section. Brittle huh.

That little lip grinder in the first pic. I've seen quite a lot of them for sale, approx US$1k out of factory. Do I look for anything in particular or are they pretty standard on the scale of things? Would be nice to sharpen even just a twist drill tbh.

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One of these machines lets you make any form of single lip engraving / milling cutters you need. (D-Bits) sharpen Reamers ends, some have attachments that you can sharpen Endmills Etc. as well

When you grind a relief add a radius on the wheel, then they won't break as easy.

There are a few things to look out for as some are not that well-built, some only have a small collet range, (which is normal for the high-quality machines), and can't do big diameter cutters, there are some though that take a standard R8 collet these do give you more range, but watch the quality of these machines, as they are not all built the same.