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Gear Hob Mandrel
- Thread starter Susquatch
- Start date
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Ok. I've only called them hobs cuz that's what I always thought they were called. Learned something new again.
So what does a gear hob look like?
If you think that is optimistic, my old MT3 shank for my own old hobs (sorry, I meant "Form Cutters") looks exactly the same! I have some fat and some skinny form cutters. All the extra sleeves, collars, and bushings live unused in the drawer. Still don't see why more than a nut and lock nut would be needed......
So what does a gear hob look like?
If you think that is optimistic, my old MT3 shank for my own old hobs (sorry, I meant "Form Cutters") looks exactly the same! I have some fat and some skinny form cutters. All the extra sleeves, collars, and bushings live unused in the drawer. Still don't see why more than a nut and lock nut would be needed......
Brent H
Ultra Member
@Susquatch: see above
Using the arbor with the spacers you can move the cutter up and down depending on need to provide clearance, you can use two slitting saws spaced out, larger body cutters - the hob for example.
Always good to have options
a hob has the rack form of the tooth wrapped around itself in a helix.....the hob and the work but rotate and are synchronized. What I meant by optimistic was the manufacture making it so long - I mean its not like on an R8 arbore you're going to have much luck using a cutter the whole length of that arbor. Was just cracking off about the maker, It'll work fine for your cutters...sorry if I confused things
this shows it pretty well
.
this shows it pretty well
.
Never mind my question about a hobb.
I found this on line:
I found this on line:
Gear Hobbing
Gear hobbing is the process of generating gear teeth with a helical cutting tool, or hob. The gear blank and hob rotate continuously until all gear teeth are cut into the blank. The speed of this process makes it ideal for large production runs.Gear Milling
The gear milling process uses a cutter, known as a form cutter, that moves axially to produce a gear tooth at the proper length and depth. After one tooth is cut, the cutter is withdrawn to allow the gear blank to rotate to the next position. Once the blank is rotated, the form cutter cuts the next tooth, and this process continues until all teeth are cut into the blank. This process is slower, making it a low production process.
Good explanation.
Guess I never hobbed a gear after all. I only form cut one....... (insert pout face here).
No biggie. One tooth at a time is fine for me.
No worries on the R8 confusion. I like my R8 Spindle. I'm REALLY impressed by what an R8 on my bigger mills can do.
I like my R8 as well....but I wouldn't run a 2" wide horizontal mill cutting in it
I did try a BIG 50 thou side milling cut on my R8 Mill at 5Hz just to evaluate VFD low speed torque. I dunno what 2" would do but 1" worked just fine. I'm guessing 2" with a little more speed would work just fine.
Those arbors come in different lengths & spacer kits BTW, you're not just stuck with that one. I guess short is generally preferred just from rigidity & runout reduction standpoint, but there may be times when the part/setup requires a longer arbor. Having a selection helps keep the bank account lean & trim.
And just to add to confusion, there are arbors conspicuously like this sold as slitting saw / jeweler saw holders which may or may not be? Often times I wonder if some of these offshore places even know what they are selling or just leave it to you figure. Some still have a key but not all blades have a key slot & also the hole dimension can vary, particularly vs. N-Am blades. With these, you might have to reverse the process - examine the nominal dimensions of blades & see what arbors(s) fit. It can be a bit of money pit depending on what path you go down. Now what I'm finding is there is a whole world of metric slitting saws out there (but which necessitates matching tooling).
And just to add to confusion, there are arbors conspicuously like this sold as slitting saw / jeweler saw holders which may or may not be? Often times I wonder if some of these offshore places even know what they are selling or just leave it to you figure. Some still have a key but not all blades have a key slot & also the hole dimension can vary, particularly vs. N-Am blades. With these, you might have to reverse the process - examine the nominal dimensions of blades & see what arbors(s) fit. It can be a bit of money pit depending on what path you go down. Now what I'm finding is there is a whole world of metric slitting saws out there (but which necessitates matching tooling).
Those arbors come in different lengths & spacer kits BTW, you're not just stuck with that one. I guess short is generally preferred just from rigidity & runout reduction standpoint, but there may be times when the part/setup requires a longer arbor. Having a selection helps keep the bank account lean & trim.
And just to add to confusion, there are arbors conspicuously like this sold as slitting saw / jeweler saw holders which may or may not be? Often times I wonder if some of these offshore places even know what they are selling or just leave it to you figure. Some still have a key but not all blades have a key slot & also the hole dimension can vary, particularly vs. N-Am blades. With these, you might have to reverse the process - examine the nominal dimensions of blades & see what arbors(s) fit. It can be a bit of money pit depending on what path you go down. Now what I'm finding is there is a whole world of metric slitting saws out there (but which necessitates matching tooling).
I hear you. Your explanation of all the bits on the arbor matches what @Brent H said. That makes sense to me.
But I'll probably be dead before I need a metric slit saw...... LOL!
Well, maybe. The way I look at it is if all I need is 'a slit' of a +/- nominal size, then I'm impartial as to IMP vs MET. Thus far my slits don't have to mate anything of critical dimension. So whether its 1/16" or 1.5mm usually doesn't affect the part. But if one can get good quality metric tooling for same or lower price than N-Am, then the Hobby Buy-O-Matic needle starts to drift that way. My experience on domestic saws is the stuff from Europe is decent, but the stuff from India is crap. For example KBC carries some from Poland & eastern block Europe. The problem is, the next nominal size may be sourced elsewhere. Then you hop to Ali & see metric equivalents for less $ or even carbide for the price of HSS here. Whether the quality is there or not is the same old story - who knows. For example my carbide threading inserts/tools are clones of Carmex but at about 1/3 price. For my purposes they work great. I've switched over to metric parting tools/inserts for the same reason. Often times the domestic tool catalogs are cagey - they might list a width as X/64" but really all they are doing is converting mm.
Agreed on all counts.
I like my R8 as well....but I wouldn't run a 2" wide horizontal mill cutting in it
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.
Chucked it up?
Ya sorry, nothing fancy, just my own shop slang for:
"I stuck a 3/4x3 inch four flute spiral end mill into a 3/4 inch R8 Collet, then shoved that assembly up the spindle, and then torqued up the draw bar."
Ok, chucked up works. I thought you were talking about the 1-1/2" thick steel reaction block
