DPittman
Ultra Member
So does it seem to be pushing/cutting hard because of the material or are you thinking it is solely because of a defective/poor quality broach?
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4140 crankshaft modifications - propeller hub build
- Thread starter phaxtris
- Start date
BaitMaster
Ultra Member
I’ve had luck with Amazon broaches in mystery steel, never known 4140.
How did it break there? Was it bending/binding?
How did it break there? Was it bending/binding?
I think it was a poor quality broach/defect, seemed to be cutting just fine, it was half way through before i heard *tink* a few more pumps (it was moving just fine, not bound) and another *tink*
it broke INSIDE the bushing/piece, where it was fully supported, so no sideways loading, i pushed the whole broach through and 2 pieces came out, i was able to push it through using a piece of 1/4" round bar held between my fingers, so no excessive pressure or im sure it would have shot that round bar out of my fingers
it broke INSIDE the bushing/piece, where it was fully supported, so no sideways loading, i pushed the whole broach through and 2 pieces came out, i was able to push it through using a piece of 1/4" round bar held between my fingers, so no excessive pressure or im sure it would have shot that round bar out of my fingers
Ironman
Ultra Member
May I suggest when broaching tough material like 4140, that you put the broach guide into the mill and deepen the slot for the broach by one shim thickness. This will take a lighter cut, you will need 3 shims instead of 2 to get to depth, and three passes. But it is easier on the broach.
Oops!
How long is your broach guide?
It needs to be at least as long (preferably longer than) as the depth of the key way you are broaching so the back of the broach is well supported as it exits the cut.
I make my broach guides between 1/4” to 1/2” longer than the cut.
I don’t have and arbour press either, so I use either a 12 ton bench top or the 40 ton floor hydraulic press.
Once the broach engages, I give it a little pump, back off the ram, re-engage the broach with the ram and give it a little more of a push. It is very slow, but works well in though materials.
+1 on @Ironman ‘s idea of reducing the shim thickness for tough material.
Speaking of shims: they too must be the full length of the broach guide, else the broach snaps like a spaghetti (don’t ask me how I found out…).
How long is your broach guide?
It needs to be at least as long (preferably longer than) as the depth of the key way you are broaching so the back of the broach is well supported as it exits the cut.
I make my broach guides between 1/4” to 1/2” longer than the cut.
I don’t have and arbour press either, so I use either a 12 ton bench top or the 40 ton floor hydraulic press.
Once the broach engages, I give it a little pump, back off the ram, re-engage the broach with the ram and give it a little more of a push. It is very slow, but works well in though materials.
+1 on @Ironman ‘s idea of reducing the shim thickness for tough material.
Speaking of shims: they too must be the full length of the broach guide, else the broach snaps like a spaghetti (don’t ask me how I found out…).
The bushing is the full length of the keyway, but not longer, i could throw it back in the lathe and make it extend beyond, there is enough material to go .200-.300 beyond
i only made one pass through, so no shim yet, i will make sure the shim is the full length of the bushing, i can see how that would snap the broach, not having support on the back
im using the 40t press, i did come off it a few times during the process to let off any possible side loading that was happening, but it broke inside of the bushing so i dont think that was the problem, i imagine it would snap above the bushing with excessive side loading
Im not entirely sold on reducing the shim thickness, each tooth that cuts sees the same doc no matter the shim, its only cutting less because you are using less teeth, i suppose that makes the broach effectively shorter, a definite benefit for side loading
i only made one pass through, so no shim yet, i will make sure the shim is the full length of the bushing, i can see how that would snap the broach, not having support on the back
im using the 40t press, i did come off it a few times during the process to let off any possible side loading that was happening, but it broke inside of the bushing so i dont think that was the problem, i imagine it would snap above the bushing with excessive side loading
Im not entirely sold on reducing the shim thickness, each tooth that cuts sees the same doc no matter the shim, its only cutting less because you are using less teeth, i suppose that makes the broach effectively shorter, a definite benefit for side loading
Well forging ahead with the magic of the dro, did up the bolt holes, chamfered, and turned the bushing so that it sticks past 2.250
the step in the bushing is to accommodate the through hole, it is relieved at the through hole for the broach to pass through
Left is the keyway and 4 holes through the barrel for a cotter pin
The hub gets shorter through the iterations, it doesn't need to be as long as the original, in fact it looks silly on the a/c, shorter is less material to remove, less weight, and less stress on the crankshaft and front bearing
the step in the bushing is to accommodate the through hole, it is relieved at the through hole for the broach to pass through
Left is the keyway and 4 holes through the barrel for a cotter pin
The hub gets shorter through the iterations, it doesn't need to be as long as the original, in fact it looks silly on the a/c, shorter is less material to remove, less weight, and less stress on the crankshaft and front bearing
That is correct.
Since your broach seems to be struggling, smaller bites may save it and thus not ruin your nice part.
She's done, broach came today, finished it off after some long overdue welding machine maintenance
Cleaned up the garage, I will try to put the crank together this week, I need to clean all of the oil passages, loctite the plugs (set screws) and install some other heat shrink parts (timing gear, cam gear)
I think I will grab 10lbs of dry ice the day I go to install the hub, give myself that extra second or two
Cleaned up the garage, I will try to put the crank together this week, I need to clean all of the oil passages, loctite the plugs (set screws) and install some other heat shrink parts (timing gear, cam gear)
I think I will grab 10lbs of dry ice the day I go to install the hub, give myself that extra second or two
@phaxtris Ryan, not sure if this would be of interest for you. Spotted on Facebook market place.
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Thanks @Perry, i did see that, and thought about it, even messaged the guy, but he knows 0 about it. I didnt think it was worth the money for a core, dont even know what the prop hub dimensions are, i think if he was asking 500 or less i would be more inclined
I was putting the motor together last weekend, but hit a snag, the rod bearings although the right size, were to tight, i have another set of bearings here on my desk and will see about putting that together tonight, hopefully they are better
I was putting the motor together last weekend, but hit a snag, the rod bearings although the right size, were to tight, i have another set of bearings here on my desk and will see about putting that together tonight, hopefully they are better
Update, Found a prop on barnstormers (not the one i ordered), installed, had to make a new front crush plate to accommodate the slightly thinner prop (bolt length issue).
been back and for to the airport getting it running, sorting out issues, i had planned to do some taxi tests and do some full power static tests and hopefully time the advance in today, but things dont always seem to go as planned. The solar charger i put on actually killed the battery (ran through a cigarette lighter, that may have been the issue), and disappearing oil. I drove all that way so i figured i should get something done, polished the windscreen, charged the battery enough to get the points to fire and run the engine. Found out my scheme to time the advance wouldn't work, chatted with the guys who flew the RV in (you can see it in the background of the video)
Came home, ordered a new battery, loaded up the truck with the extra oil, extra plugs, etc. wont let something silly like that stop me next time. The next time i go out i will top the oil off, and monitor through the ground runs, see if i can find what happened to the bulk of the oil, maybe i didnt have it topped off to begin with, or it disappeared into the nooks and cranny's of the engine (after first start) or maybe over the months the engine sat on the plane it dripped from some slow leak, that will have to be sorted out in any case.
Came up with a new idea to time in the full advance, the original plan was to time off my marks on the back of the engine with the phone clamped to the timing light videoing, well cant see the marks from the phone where the timing light needs to go. I will need to time off the back of the prop spinner, made up a quick program and cut out two timing tabs to rivet onto the back of the spinner flange, i will have to make a pointer on site, and some way to clamp the timing light to the oil cooler im thinking.
been back and for to the airport getting it running, sorting out issues, i had planned to do some taxi tests and do some full power static tests and hopefully time the advance in today, but things dont always seem to go as planned. The solar charger i put on actually killed the battery (ran through a cigarette lighter, that may have been the issue), and disappearing oil. I drove all that way so i figured i should get something done, polished the windscreen, charged the battery enough to get the points to fire and run the engine. Found out my scheme to time the advance wouldn't work, chatted with the guys who flew the RV in (you can see it in the background of the video)
Came home, ordered a new battery, loaded up the truck with the extra oil, extra plugs, etc. wont let something silly like that stop me next time. The next time i go out i will top the oil off, and monitor through the ground runs, see if i can find what happened to the bulk of the oil, maybe i didnt have it topped off to begin with, or it disappeared into the nooks and cranny's of the engine (after first start) or maybe over the months the engine sat on the plane it dripped from some slow leak, that will have to be sorted out in any case.
Came up with a new idea to time in the full advance, the original plan was to time off my marks on the back of the engine with the phone clamped to the timing light videoing, well cant see the marks from the phone where the timing light needs to go. I will need to time off the back of the prop spinner, made up a quick program and cut out two timing tabs to rivet onto the back of the spinner flange, i will have to make a pointer on site, and some way to clamp the timing light to the oil cooler im thinking.
Well, a cell phone is not ideal to video the timing light, the frame rate is far to low, but i did manage to get some video and it did help me correct the timing.
First full power static runs i did have some large bogs and flat spots, i was able to get the engine to run 2800rpm, i was videoing for these runs and managed to note the timing far to advanced, over 32degrees at full throttle, and what looked like 23-25 degrees idling 700ish rpm (the advance springs must be extremely light), full trot i should only be seeing 28 degrees. With the new timing tab i was able to set the static timing to 3deg'ish BTDC (from 6ish) , That small change made starting a heck of a lot easier, it also cleared up those bogs/flat spots and now makes 2900rpm. I did not video another full throttle timing run.
The video is a start/idle , this is a hot start with the timing at 6deg static, very hard starting, need a fair bit of throttle, and even though it is tied down very well, you can still see me sprint around to pull the throttle back. You can see how difficult it is to see the timing, its noticeable around the 35 second mark. With the timing set to 3deg static it will now start hot with 0 throttle, just a hurried walk around instead of the full on sprint.
The goofy rig holding the timing light with my cell phone clamped to the front. You cant see but i have a "baby bessey" clamping it down, the tape just stops it from bouncing around
View from the cell, you can see the site made timing tab, as well as the cnc cut timing marker riveted to the lip of the spinner
some screens
One of two problems i have to deal with now, the prop hub absolutely pisses oil, vw never used a seal, aerovee doesnt use a seal, great plains used a seal jb welded to the front of the case. Im thinking that if i can find some seal rope/rope seal i may sew it around at the base of the prop hub and jb weld it into place, or possibly make a holder for the rope seal and jb weld the holder in place. I think i made the clearances to tight and it has some kind of capillary action, vw probably didnt make that hub with .005 clearance. Anyone know where to get seal rope in the 21st century ? i think thats my best option, i dont care if it leaks some, it just needs to be a manageable amount.
this is where i have to stuff a seal in
One of my wifes old sheep skins she told me to throw away....never throw anything away.....hopefully it will stop the tarp from buffing the heck out of the windscreen
First full power static runs i did have some large bogs and flat spots, i was able to get the engine to run 2800rpm, i was videoing for these runs and managed to note the timing far to advanced, over 32degrees at full throttle, and what looked like 23-25 degrees idling 700ish rpm (the advance springs must be extremely light), full trot i should only be seeing 28 degrees. With the new timing tab i was able to set the static timing to 3deg'ish BTDC (from 6ish) , That small change made starting a heck of a lot easier, it also cleared up those bogs/flat spots and now makes 2900rpm. I did not video another full throttle timing run.
The video is a start/idle , this is a hot start with the timing at 6deg static, very hard starting, need a fair bit of throttle, and even though it is tied down very well, you can still see me sprint around to pull the throttle back. You can see how difficult it is to see the timing, its noticeable around the 35 second mark. With the timing set to 3deg static it will now start hot with 0 throttle, just a hurried walk around instead of the full on sprint.
The goofy rig holding the timing light with my cell phone clamped to the front. You cant see but i have a "baby bessey" clamping it down, the tape just stops it from bouncing around
View from the cell, you can see the site made timing tab, as well as the cnc cut timing marker riveted to the lip of the spinner
some screens
One of two problems i have to deal with now, the prop hub absolutely pisses oil, vw never used a seal, aerovee doesnt use a seal, great plains used a seal jb welded to the front of the case. Im thinking that if i can find some seal rope/rope seal i may sew it around at the base of the prop hub and jb weld it into place, or possibly make a holder for the rope seal and jb weld the holder in place. I think i made the clearances to tight and it has some kind of capillary action, vw probably didnt make that hub with .005 clearance. Anyone know where to get seal rope in the 21st century ? i think thats my best option, i dont care if it leaks some, it just needs to be a manageable amount.
this is where i have to stuff a seal in
One of my wifes old sheep skins she told me to throw away....never throw anything away.....hopefully it will stop the tarp from buffing the heck out of the windscreen
Can you take that flange off without dismantling the engine ?
If you could, what about making a round seal holder with a flange with say 8 small screws or bolts that you attach to the front of the block, slop some RTV under it. There is probably a seal available, hydraulics shop, or getting one made isn't too bad, at least they weren't 30 years ago last time I got some.
If you could, what about making a round seal holder with a flange with say 8 small screws or bolts that you attach to the front of the block, slop some RTV under it. There is probably a seal available, hydraulics shop, or getting one made isn't too bad, at least they weren't 30 years ago last time I got some.
i could probably get it off, but getting it back on is an issues, interference fit, have to heat it up to 450 deg to get it back on. So the re-install would probably cook to seal
some guys cut a something like a axle seal in half and jb weld it in place, i didnt leave enough straight shaft i think for something like that, either it needs to extend far to the straight section, or the seal would be running on the taper, not sure how well running on the taper would work with a standard rubber seal
i was thinking it might be possible to use something like this
i could put that around the base of the flange where it meets the case, tighten it around with some form of clamp, and jb weld the whole shebang onto the case