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Gear Hob Mandrel

YYCHM said:
Ok, chucked up works. I thought you were talking about the 1-1/2" thick steel reaction block:rolleyes:
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2-1/2 @YYCHM! Not 1-1/2!

Two point five, 2.5, two and a half.

That was one very big cut for a home shop machine running at practically zero - just 5 hz. Nothing bent, nothing moved, nothing complained. I was sooooo impressed! And it's perfectly square too!
 
Susquatch said:
2-1/2 @YYCHM! Not 1-1/2!

Two point five, 2.5, two and a half.

That was one very big cut for a home shop machine running at practically zero - just 5 hz. Nothing bent, nothing moved, nothing complained. I was sooooo impressed! And it's perfectly square too!
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Oooops :oops: Where the heck did you get a 3/4" endmill that has 3" long flutes? Need to see a pic of that pls.
 
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YYCHM said:
Oooops :oops: Where the heck did you get a 3/4" endmill that has 3" long flutes? Need to see a pic of that pls.
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I got it with my mill drill when I bought that. All the goodies I got with that machine were worth three times what the machine was worth. It was a comical situation. When I picked up the mill/drill the fellow who sold it to me was moving - I think he said over seas. Anyway, he helped me put the machine in my pickup truck box. Then he just started loading other stuff in there too. I never knew I was getting anything but the mill/drill itself. The accessories included a strong metal stand, some measuring tools, a universal dividing head, a tailstock, a 5C rotary divider, two big vises, and boxes and boxes and boxes of tooling, Collets, Mandrels, arbours, gear cutters, slit saws, etc etc. My eyes just kept getting bigger and bigger. After a while I was starting to think he was gunna throw his wife in there too!

The end mill is a big one for sure! It's almost 8 here now and the coyotes are howling. I'm scared of the dark. So I'll take a photo for you tomorrow some time after the sun comes up..... LOL!
 
YYCHM said:
Oooops :oops: Where the heck did you get a 3/4" endmill that has 3" long flutes? Need to see a pic of that pls.
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Got to the shop for a bit before heading out into the fields.

Here is a photo.

20211122_115557.jpg


I added the skinny tape measure and 1/8 end mill just because I know how much optical illusions like to follow you around...
 
Or maybe this one is a bit more to your liking.....


20211122_120931.jpg


Sorry, devil made me do it....
 
But just think @YYCHM ...... My Hartford actually turned that monster at just 5hz and carved (better choice of words than milled) off 30 thou over 2.5 inches in just one pass! The feed rate was not unreasonable either.

I'm absolutely stunned and amazed!

I'll prolly never do it again, but had to try it just to see what she could do! Obviously, since she didn't complain, she can prolly do much much more than that but...... That will certainly do!
 
Susquatch said:
So, I was straightening a big bracket on my 30 ton shop press and I noticed that one of my big steel reaction blocks was badly out of square.

Hmmmmm says I! Nice chance to checkout 2" side milling on the Hartford. Actually it turned out to be 2-1/2 inches. Perfect job for my big 3" x 3/4" end mill.

Chucked it up and had at it. Took 5 passes at 20 thou to get it square and one pass at 30 thou to try and make it complain.

So this is 30 thou over 2.5 inches at just 5Hz on the VFD. It didn't whimper at all. Just got down to business and cut like butter.
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I just did the bearings on my XLO last year.....expensive so my thought was fuelled mostly by not overtaxing the light nature of the spindle. Point taken, there is no rule that because its a 2" cutter you can't just take super light cuts. The comparison is a bit apples to oranges though as a 3/4 cutter needs less torque than cutter that'll fit on that arbor.

btw....that cut, how long did take and how many HP is the mill?
 
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Susquatch said:
But just think @YYCHM ...... My Hartford actually turned that monster at just 5hz and carved (better choice of words than milled) off 30 thou over 2.5 inches in just one pass! The feed rate was not unreasonable either.

I'm absolutely stunned and amazed!

I'll prolly never do it again, but had to try it just to see what she could do! Obviously, since she didn't complain, she can prolly do much much more than that but...... That will certainly do!
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Well... Ya, I'm impressed to. But your machine is 6 times heavier than mine. I'm finding my 1/2" carbide 4 flt endmill does well side milling as well. I'd like to get some 3/4" carbide endmills with longer flutes, but where? I don't think I'd have enough torque at 5hz to do anything, 20 seems to be the limit.
 
I would have lost a 1 coffee bet that the big end mill would be spinning inside that R8 collet at that DOC removal rate. I guess one doesn't know till one tries.
 
Susquatch said:
But just think @YYCHM ...... My Hartford actually turned that monster at just 5hz and carved (better choice of words than milled) off 30 thou over 2.5 inches in just one pass! The feed rate was not unreasonable either.

I'm absolutely stunned and amazed!

I'll prolly never do it again, but had to try it just to see what she could do! Obviously, since she didn't complain, she can prolly do much much more than that but...... That will certainly do!
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This 30 thou term confuses me, are we talking 0.03" ? I go 0.05" or more all the time:p

My recent gear cutting exercise included a DOC to 0.13".
 
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Mcgyver said:
I just did the bearings on my XLO last year.....expensive so my thought was fuelled mostly by not overtaxing the light nature of the spindle. Point taken, there is no rule that because its a 2" cutter you can't just take super light cuts. The comparison is a bit apples to oranges though as a 3/4 cutter needs less torque than cutter that'll fit on that arbor.

btw....that cut, how long did take and how many HP is the mill?
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It is a 2HP VFD Rated motor. The cut wasn't fast like doing a half inch face cut, but no slouch either. I didn't time it. I'd say one or two minutes for a 5" pass. It wasn't throwing big huge swarf - just shavings. I could have pushed harder but that didn't seem wise.
 
YYCHM said:
Well... Ya, I'm impressed to. But your machine is 6 times heavier than mine. I'm finding my 1/2" carbide 4 flt endmill does well side milling as well. I'd like to get some 3/4" carbide endmills with longer flutes, but where? I don't think I'd have enough torque at 5hz to do anything, 20 seems to be the limit.
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Some will debate this matter, but most motor/vfd combos are constant torque from the rated rpm down so available torque is unlikely to be an issue. The real issue is feed/metal removal rate. In other words, a slower cut should not really be an issue provided you have adequate motor cooling.

But then again, why? I was deliberately testing my machine. Normally, I would make that cut at the recommended rate for the material, or as a rough guess, I'd prolly aim for 900 - 1000 rpm on a 3/4 bit and I wouldn't take off nearly that much in a single pass - maybe 5-10 thou or so. Im not in a race and time is not money for me.

That's the simple version from my perspective anyway.
 
YYCHM said:
This 30 thou term confuses me, are we talking 0.03" ? I go 0.05" or more all the time:p

My recent gear cutting exercise included a DOC to 0.13".
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Ya, 30 thou is 0.030. And ya, one can go more or less depending. I just figured 30 thou was a very respectable cut that I could really test my machine at. Nothing more or less.

Like you I have been routinely taking off a quarter inch at a crack on smaller end cuts.
 
This is also function of sharpness of the EM & hardness of material - a dull carbide EM in 3/4 I usually go max 120 thou in single pass max in something like 4140 with around 900 rpm speed. Feed at 4ipm 4 flute giving me about 1+ thou cut per tooth.
Yes technically I should have higher RPM and higher feed rate for the machine but I don't want it walk out the door ;)

This is with BP style machine.
 
Tom Kitta said:
This is also function of sharpness of the EM & hardness of material - a dull carbide EM in 3/4 I usually go max 120 thou in single pass max in something like 4140 with around 900 rpm speed. Feed at 4ipm 4 flute giving me about 1+ thou cut per tooth.
Yes technically I should have higher RPM and higher feed rate for the machine but I don't want it walk out the door ;)

This is with BP style machine.
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Sounds a lot like experience talking. I'd be happy with that too!
 
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