Another gear ?

B

Bob Kelly III

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Well , I went out to the tiny shop and was going to practice threading again , but I got derailed ! ... when I made my larger threading dial, I laminated 2- 3/16"disks of aluminum together by riveting them at 4 points around the disks.... ( I used the saw blade indexer and it worked fantastically )
and I got to thinking why not just make a aluminum gear for that idler gear that is so banged up ? I could do the same , laminate the sheets together to have enough thickness and then cut the teeth into the gear blank.... so I went to my bucket of aluminum scrap and I saw a chunk of 3/4"x3" x 18" or so aluminum from my old
gyro copter..( i made a 4' hub bar for it , and this is what was left of it ).... so I thought hay that is the right thickness...no lamination needed ! that's a big plus ! so I cut a 3"x3" hunk off that bar drilled a 7/16" hole for a bolt to go through the center and act as a mandrel and then chucked it up in the lathe and started the intermittent cut
of getting that square piece round.....it's slow going but i'm about halfway to round ! LOL....
the plan is to make it the same diameter as the busted gear and then bore the hole to fit the bolt that goes through it.... then trim it to the same width of the bad gear....
once that is done I can then just mill the teeth into it on the 3 in 1 's mill and hopefully I will have a new gear that I can replace the bad one with !
.....that and I finally got around to finish taking an old electric stove apart and cutting it up into pieces....
.....I really need to go by the scrap yard in town and get some thick steel I have no 1/2" plate at all, and have a need for at least 1 90 degree plate for the lathe
I want to make a milling attachment for it ! but I can't even get started on it without some decent material to work with ! 1/2"x 1-1/2" bar stock would be real nice too !
.....
anyway.....that's what I did F.W.I.W. LOL.......
Bob......
 
well, I got the square hunk of aluminum round and then trimmed down to width all that remains is boring it to size and then cutting the teeth
..... I bought a battery for the digital caliper today, which cost me half as much as the whole caliper did ! LOL
$5.75 for the tiny battery ! that is outrageous !
but the calipers do work now and just in time to get the dimensions right on the gear blank...
( I am .001 off on gear thickness , but dead on in gear diameter ! )
boring that hole accurately will be a challenge for me...I drilled the center hole to 1/2" but the next size drill but I have is too big
so I will just bore the hole on the lathe.... but finding something to bore that 1/2" diameter hole isn't easy ! but I found a 1/4" carbide cutter that
should do the job.... I hope ! i think if I go in a bit askew.... I can get the thing to cut without chattering or trying to cut with the whole face of the tool
if need be I can grind that tool to suit the job !
the problem will arise when I try to anchor that tiny tool in the 1/2" tool holders of the tool post ! but i'll figure out something !
....
I probably spent an hour whittling down the big hunk of aluminum ! and getting it down to size....
I used the power feed and took 20 thousandths cuts through most of it I couldn't go any more aggressive than that because of the bolt arbor I was using to hold it on there.... as it was I sheared off one bolt and had to find another.... and I spun the blank on that bolt anyway... but I did get to hog off metal when I was taking it to thickness... it felt really good seeing big chips for a change ! LOL.....
....
on 98% of the taking the diameter down....past the intermittent part, when it was finally round,( about 1" to remove from the diameter ! ) I finally found the sweet spot for breaking the chips ,....and only got a few long stringers.... those things are dangerous as hell ! and they get in the way !
( but do not remove them with your hand !!!!...turn off the machine before you touch them ! )
but most of the chips were an inch or less in length and that suited me just fine ! so I continued with that speed and depth through the whole ordeal !
I will try aluminum on steel as the bearing surface... I can always bore it further out and put in a copper bushing if needed ! i have a feeling the gear will outlast me,.... when I'm done with it ! ( at least I hope so !)
....later !
Bob.......
 
well, that gear blank was over bored even for the bushing.... and the teeth were out of alignment.....
so i made another gear blank today, this one only took me a few hours compared to a full day with the other one.
So..... I made another gear blank, and got the dimensions spot on ( without going over ! )
this time I used the dials on the lathe
and did some quick math in my head
and zeroed the collar on the cross slide and just subtracted the depth of cut and zeroed in on that puppy quick and easy ! ....
the bolt that holds the idler gear on has several steps in it and the one step that holds the gear is .625" in diam the hole for the center of the gear blank is exactly .62".... yet it fit on easy......i find that kind of odd..... and I am thinking my calipers aren't very accurate because of that ! it only has 2 places past the decimal point.... so it may well be .628" and that's why it fits so easy....
maybe Santa will bring me a digital caliper that has 4 or 6 places after the decimal LOL
....
but I was quite happy with the outcome of this gear blank....
.....now all I gott'a do is put 34 teeth on it ! LOL..... ( that's all ! as my mother used to say "the impossible is only a little bit harder Son !")
....
later all !
Bob........
 
Don't trust those calipers for internal measurements. We hired a newbie here. Had machine shop teaching experience on his resume. I ended up having to show him my telescoping gauges and give him the correct measurements for some pulleys he was trying to measure with calipers. He had the same problem as you. Make a plug with your lathe with the correct diameter.
 
well, yesterday I crept up on the dimensions and didn't have any trouble with the I.D...... problem is I did the same thing the day before and it was way off.... i dunno,.... I'm doing something I shouldn't LOL..... i expect it is not having that 3rd digit place in my cheap calipers !
.... having a telescoping I.D. tool that you can Mic must be nice !.... i am what they call "measuring tool deficient" here<grin>
.....
this morning I started making a new indexing jig for the mill.... much like the last one, except this will have the original gear stacked on the same shaft
and this one is for making a completely new gear, not just repairing an old one.
though it will have a pin for the teeth to index with you won't be cutting right there you'll cut over about 1/2" on the gear blank, the old gear is just on there to index the new gear with !
.... I still need to make a pin,.... to pin the 2 gears together with, so both will have to be drilled for that said pin...but that will keep the gears from turning with respect to each other.
I will do that by drilling a 1/16" hole all the way through the gear blank and into the original gear to make sure both are centered ( while on the jig)
then enlarge that hole on the inside of the 2 gears with a 1/8" bit and use a steel rod as a pin.... that way the pin is captured as long as they are together on the jig.... and I can't have it fall out and allow them to turn . it needs to be secure.
.....
I also have to re make my gear tooth cutter as it is not uniform and is too wide at the base.... my decade old fly cutter worked well but the profile I ground into the tooth cutter lacked allot ! LOL..... so I gott'a re make it ! ( it is just a 2" piece of an old file ground into the profile of a tooth, that fits in a slot on the fly cutter I made ages and ages ago )
.....
we'll see how far I get on the build today.... I'm on my 2nd cup of coffee ! HAHAHAHAHA
C ya !
Bob..............



....
 
well , I didn't get too far.... I just got the pin done in between the gear and gear blank is all....
Bob.....
 
ok... here's my theory in a gear making jig for a milling vice and why it should work....
what we need to do is measure the exact center from tooth root to tooth root in 2 good teeth on the old bad gear.... that distance
needs to be incorporated into the pin placement or tooth nock at the back of the jig....( that is the "off set")
so if the tooth notch at the back of the jig is fixed in place you will have to either raise or lower the cutter ( if your using an arbor and tooth cutting tool like I wish I had, you must keep that centered at the gears parallel line, and rotate the gear slightly by raising or lowering the tooth notch somehow..... ( so it shouldn't be fixed in position! it has to move at least the distance between the center of 2 teeth notches ) on my gear that is less than 3/16"
....so if you set up the jig correctly and it is set so that the gear is rotated ( horizontally) just the right amount you can cut your 2nd notch.
(the first notch doesn't matter where it is at everything will correlate from that first notch .)
now with the second notch cut you flip the gear over ( horizontally) and put that notch in the tooth nock of the jig.... if the cutter lines up exactly fantastic...
flip the gear 180 degrees (vertically ) and it should be ready for the next tooth valley to be cut. (because of the "off set")
then you put that fresh cut in the jig's tooth notch and do it again and work your way around the gear one tooth at a time.
.....
You might note that this isn't the idea of stacking 2 gears the bad one and the good new gear blank and going for it.... this goes back to my original idea when using a gear repair fixture for a single gear that you braised up.....
with that rig you can position it on any tooth valley on the pin and be lined up with the cutter automatically, it's a set it and forget it routine !
....
but what if I wanted to make a entirely new gear out of aluminum ? hence the stacked version bad gear then gear blank as long as your lined up with the tooth valleys on the bad gear you can cut the new notch in the gear blank .... it has the same pin idea as the older repair version...
it's just wider to allow 2 gears
....
either way ya go it can be done in my book.... either the stacked version or the flip flop version
and with the flip flop version you don't need a complete gear to do it, just the measurements between tooth valleys to set the off set of the jig's tooth/pin....
......
later all !
Bob.........
 
ok, I got the jig welded up, the movable tooth done and bolted on with a 1/4" x 28 tpi bolt about 1/2" long and it is the perfect length i really lucked out on that one !
so all in all the jig is done for the double gear idea.... now all I have to do is make a new cutter for the fly cutter to match the tooth profile and then give it a go.
each tooth will be cut to depth before moving on to the next one, the fewer the times I have to take it out of that mill vice the better !
......
so soon as I get the courage up to give it a try, and risk a full days work on the gear blank I'll attempt to cut a new gear from scratch out of aluminum !
.....
I might practice on the old gear blank that I think I screwed up..... first...and see if I run into any unforeseen problems !
.......
it looks good.... solid and ready to use, i don't think I'll have any problems with it !
it looks almost identical to the first "self indexing gear repair tool, except that this one has a longer pin for the gears to set on and the pin on the left is not a nail but a piece of 1/4" x 1" bar stock with a single tooth carved into it to engage into the bad gear , this bar stock had a slot in it so it can move forward and back and it clamps down nice and tight with the fine thread bolt I put in it !
...sorry no pictures the wife has been using her phone all day ! LOL.....
....
Bob.........
 
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