Topic: DIY back-cut tranny questions.

[754]

 Well some of us arepolitely pointing out what will be needed, and what will happen to select tools using these parameters.
 Hey I tried grinding a disc with a large mounted point, on the mill... Using a rotary table...with dismal results. Tried it on a surface grinder too, using a rotary table, tried it till I got tendonitis from cranking the 90:1 table.....learned something..need a driven table..
 Somethings you just got to find out yourself, but finding root cause of it not working is part of the learning.
 Like I said..probably possible. Without the drill press, using mounted points.. On die grinderor handgrinder...the trick is the fixtures..

[scottly]

Well some of us are politely pointing out what will be needed, and what will happen to select tools using these parameters.

1+

[2wheels]

I was just happy fang provided some great picture to describe what you are all talking about.  Now I'm really learning.

I have a outboard motor that will not stay in gear, similar problem as described here.  Now I know the dremmel tool is the only option.  And it won't work perfectly when I'm done. 

[754]

 There is people that can, and have done it with a dremel tool..
 And there are those that would never figure it out, even with a rotary table, tool and cutter grinder, and surface grinder.




 Most of us fall somewhere between those two examples..

[phil71]

I'm reading about DIY brain surgery now. it doesn't seem so hard!

[754]

 Might be iPretty easy if you got spare brains to try it on...

[scottly]

Sometimes it's harder to teach a young dog old tricks, than to teach an old dog new tricks..

[lostinthe202]

I'm reading about DIY brain surgery now. it doesn't seem so hard!

Hehe

Well some of us are politely pointing out what will be needed, and what will happen to select tools using these parameters.
 Hey I tried grinding a disc with a large mounted point, on the mill... Using a rotary table...with dismal results. Tried it on a surface grinder too, using a rotary table, tried it till I got tendonitis from cranking the 90:1 table.....learned something..need a driven table..
 Somethings you just got to find out yourself, but finding root cause of it not working is part of the learning.
 Like I said..probably possible. Without the drill press, using mounted points.. On die grinderor handgrinder...the trick is the fixtures..

Well, if you're trying to be so helpful, how about a detailed description of what grinding setup you'd use?  Please include tools, speeds and feeds, coolants, machines involved, and the necessary jigs in place of the vague descriptions you've offered.

If, as you say, " the trick is in the fixtures" how about some workable descriptions of what those fixtures would be?  Or how about offering some advice on what speeds and feeds Fang should be using with the tooling he's bought.

Nobody asked you to post a response, It's like your mom told you all those years ago, if you don't have anything nice to say....

[754]

I did say early on use stones..mounted Points..in a die grinder, and turn that around the round dog on the inclined gear, that should be indexable. The flat ones are easier. After I saw the drill press, I know. That the spindle will move over. He has a crosslide, he can use that for infeed...
 A diegrinder bolted to the head casting is far more rigid than the drill spindle.

[phil71]

" Might be iPretty easy if you got spare brains to try it on...".
 
----abby-something..

[crazypj]

Might be iPretty easy if you got spare brains to try it on...

Still laughing

[crazypj]

aw comon' fellas, don't you remember what it was like to get something flat within a half a thou (or .015mm for you tea drinkers ) on a knee mill just to see if you could even though the tolerance was wide open?  Or how about cutting a multi-lead thread just to see if it would work?  Or squaring a block in a 4 jaw?

sounds like you trained the same as me

[lostinthe202]

Yup.  Strange time to be a machinist employment-wise, but for better or worse that's what I'm doing!

[iron_worker]

Just in case you haven't heard enough of my thoughts ... lol

Have you considered removing the existing dogs and drilling/reaming a new hole for a tight press fit of hardened pins?

IW

[alancop]

Just in case you haven't heard enough of my thoughts ... lol

Have you considered removing the existing dogs and drilling/reaming a new hole for a tight press fit of hardened pins?

IW

I have been following this thread since it's inception, just to see what you eventually decided to do. This^ post is the best Idea have seen so far, all you would need is a 10mm drill and a way to jig up your gears at that 2 degree angle. Then just drop some 10mm hardened steel pins in and lock them in with flat spotting or possibly a set screw... I'm taking machining classes at my local tech school, so I'm not an expert like a few people in this thread, but it made sense to me.

[lostinthe202]

Just in case you haven't heard enough of my thoughts ... lol

Have you considered removing the existing dogs and drilling/reaming a new hole for a tight press fit of hardened pins?

IW

I have been following this thread since it's inception, just to see what you eventually decided to do. This^ post is the best Idea have seen so far, all you would need is a 10mm drill and a way to jig up your gears at that 2 degree angle. Then just drop some 10mm hardened steel pins in and lock them in with flat spotting or possibly a set screw... I'm taking machining classes at my local tech school, so I'm not an expert like a few people in this thread, but it made sense to me.

The first thing to deal with if something along this route is to be followed is that the gears should really be annealed.  Even if these are made from a lower carbon steel and just case hardened, that's still maybe .060 of hardened material you'd need to get through.  They could be 4140 or such that could be hardened through.  Drilling hardened materials (like HRC 55 or so and below) is possible with carbide drills (expensive) but as has been stated in this post already, carbide demands certain conditions and one of those is even cutting pressure which you really can't achieve using a manual quill.  This doesn't have as much to do with the rigidity of the machine as it has to do with the rigidity of the arm.  It's not really possible to maintain a constant feed by hand, you might get off to a good start, but if you hiccup along the way, often you're toast. 

Seems like if you were going to go the route of drilling and pressing new pins in, you'd be doing that to avoid having to setup funky angles and the difficulties of indicating your position at that angle.  If you're flat and you've got that nice round dog sticking up, you can sweep it with an indicator and center on it really easily.  Once you're at an angle you're dealing with an oval so sweeping becomes taking an average.  There's ways around this of course, tooling balls or a jig with a location method included, but the more complicated you make things, the longer it takes and the more chance you have to introduce error.

Then even if you drill out and press in pins that you had an angle turned on by somebody, then you've still got to setup and machine the mating surfaces on the matching gear.  After that you'll need to re-harden and temper the gears.

Some good reading on backyard metallurgy (post number 7)
http://www.practicalmachinist.com/vb/fabrication-cnc-laser-waterjet-plasma-welding-fab/surface-hardening-oxyacetelyne-132029/

[lostinthe202]

alancop,

I like your triple clamp, did you make that at school?

I think it's great you're taking classes at your local JC.  I wish more people who have an interest in machining (like people who populate boards like this one and others like it) would take those classes just to keep the enrollment numbers up and the funding coming in so they don't all go away.  There are a lot of good programs taught by people who learned their trade before computers did everything for you. 

"CNC is just another tool an experienced machinist uses."   My favorite saying from one of, if not the, sharpest machinist I ever met.  This guy didn't cut soft jaws, he used parallels and v-blocks and angle plates and indicators for everything.  +/- .001" was a wide open tolerance for this guy.  It's getting a lot harder to find that kind of knowledge these days.

anyway, hijack over!

[geminimotors]

If we're too hard on the man, we'll piss him off and he won't be here to regale us with his tales of victory, defeat, or the valley between, and won't be here to benefit from or contribute to our lil think tank. This aint a swordfight, so let us zip up the swagger sticks and see where this goes.
 Lostinthe202- Amen on the trade school angle. A book we all should read: http://www.matthewbcrawford.com/

[dave500]

using knock in pins is doomed i think?too much risk of obvious failure.

[crazypj]

 +/- .001" was a wide open tolerance for this guy.  It's getting a lot harder to find that kind of knowledge these days.

It still is for some projects 
0.0005" (half a thou) isn't too difficult to achieve even on Chinese hobby machines
CNC is great if you have it (and need a million parts)

[70CB750]

alancop,

I like your triple clamp, did you make that at school?

I think it's great you're taking classes at your local JC.  I wish more people who have an interest in machining (like people who populate boards like this one and others like it) would take those classes just to keep the enrollment numbers up and the funding coming in so they don't all go away.  There are a lot of good programs taught by people who learned their trade before computers did everything for you. 

"CNC is just another tool an experienced machinist uses."   My favorite saying from one of, if not the, sharpest machinist I ever met.  This guy didn't cut soft jaws, he used parallels and v-blocks and angle plates and indicators for everything.  +/- .001" was a wide open tolerance for this guy.  It's getting a lot harder to find that kind of knowledge these days.

anyway, hijack over!

Yeah, that is a difference between machinist and machine operator. 

[lostinthe202]

Lostinthe202- Amen on the trade school angle. A book we all should read: http://www.matthewbcrawford.com/

Ha!  Excellent book.  I've given it as a gift to various people a number of times.  I think it should be mandatory reading in high school in this country.

[iron_worker]

using knock in pins is doomed i think?too much risk of obvious failure.

Mind expanding your thoughts a little more as to why?

IW

[70CB750]

Heat dilatation?

I don't think pressed piece would go anywhere when properly designed and installed.

[754]

 Three things come to mind, harder to drill it out than to backcut it, itcould move, drilling thru the gear will weaken it.
 Imo if you can drill itbout, you can properly back cut it.