Where is that?
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Internal splines
- Thread starter Garyt
- Start date
Where is that?
Dabbler
ersatz engineer
@Garyt I agree that using a mill and rotary table with a shaping bit is going to get you your piece the best way out of a myriad of sub-optimal choices.
100% agree that this method requires .001-.0015 per stroke *maximum*. The tool bit will have to be resharpened and re-aligned after each pass, if HSS and cast iron are the materials.
With a shaper head on a BP style machine, it can be done easier and somewhat faster, but the setup time will average the total time out, pretty much.
100% agree that this method requires .001-.0015 per stroke *maximum*. The tool bit will have to be resharpened and re-aligned after each pass, if HSS and cast iron are the materials.
With a shaper head on a BP style machine, it can be done easier and somewhat faster, but the setup time will average the total time out, pretty much.
To do this on a lathe two things are required.
1. A method of indexing the spindle
2. What I called Broach mode on my ELS.
Cutting an internal slot on a lathe is no different from internal threading. You make multiple passes indexing away from the center line on each pass until the correct depth is reached and then a few spring passes. On the return pass, like threading the tool is pulled from the work. Except with a broach mode the spindle is held solid and there is no fault raised because the spindle is motionless.
If the load is too heavy for the width required then a narrower cutter is used and the spindle is indexed appropriately.
One other similar thing to threading is you need a run out area at the end of the slot. The alternative is a ramp at the end of the slot so the tool never actually runs into an obstruction. My ELS cannot do the ramp. Really CNC is the only easy way to do that part.
The advantage of the 'threading' approach is the tool doesn't drag backwards along the slot.
1. A method of indexing the spindle
2. What I called Broach mode on my ELS.
Cutting an internal slot on a lathe is no different from internal threading. You make multiple passes indexing away from the center line on each pass until the correct depth is reached and then a few spring passes. On the return pass, like threading the tool is pulled from the work. Except with a broach mode the spindle is held solid and there is no fault raised because the spindle is motionless.
If the load is too heavy for the width required then a narrower cutter is used and the spindle is indexed appropriately.
One other similar thing to threading is you need a run out area at the end of the slot. The alternative is a ramp at the end of the slot so the tool never actually runs into an obstruction. My ELS cannot do the ramp. Really CNC is the only easy way to do that part.
The advantage of the 'threading' approach is the tool doesn't drag backwards along the slot.
Our project is at Bomber Comand museum in nanton
I'm not understanding that, imo the only time CI and HSS are an issue is if taking of a sand ridden outer crust, otherwise HSS wears well with CI.
I've not cut an internal spline, but I have done some largish keyways. Its obviously a challenge to take a 1/2 wide cut in 2" material by plunging a tool with quill but there is no law that says you can't use a 3/16 or 1/4 wide cutter and step it over. irrc I also plunged with slot drill first to remove as much as possible.
More steps adds to the tedium, but perhaps a similar approach would be make it possible?
historicalarms
Ultra Member
One of my greatest disappointments of late is that a neighbor of mine for 20 yr had a stroke & passed this year. I discovered after the stroke disabled him that he was a WW II Mosquito pilot...had I known that beforehand, i would have certainly made an effort to get him to tell me the stories...stories that are dead now.
Garyt, although I have never seen it, I understand there is a dedication at the museum to a man, Percy Waddy. His brother and nephew were/are the lifelong best friends and neighbors of My dads and I. With his Bomber Command time & the rest of his life as a RCMP constable, "Perc" had a very full life.
Back to the internal spline topic, some of the most accurate rifle barrels in the world are broach cut for lengths of over 30". We in Ab are lucky to have two of the most renowned "barrel cutters" In North America. One in Red Deer and the granddaddy of them all at Rural Torrington .
If they can broach a barrel to put a .300 bullet into a spot the size of itself at 500 M then cutting a slip fit spline should be doable with the most rudimentary set up.
@Garyt, I am sure we will be able to help you make the part.
I have helped Jack McWilliam (not sure if he is still helping with the Mosquito at Bomber Command in Nanton) on his Hawker Hurricane project up in Wetaskiwin where I made parts for the landing gear/flap hydraulic actuator.
As soon as you have details of the part, please post it here and we’ll figure out how to make it for you.
You / Jack can also PM me if you want.
Cheers, Rudy
I have helped Jack McWilliam (not sure if he is still helping with the Mosquito at Bomber Command in Nanton) on his Hawker Hurricane project up in Wetaskiwin where I made parts for the landing gear/flap hydraulic actuator.
As soon as you have details of the part, please post it here and we’ll figure out how to make it for you.
You / Jack can also PM me if you want.
Cheers, Rudy
Tom Kitta
Ultra Member
Even with a shaper that is needed if the rod holding the HSS is not exactly very thick.
CI is definitely much easier than steel - steel say 4140 is not exactly easy.
What would happen if you pre-drilled the splines then squared them out with your lathe indexing set up? Drilling wouldn't have to be super accurate and would get rid of the bulk of the material.
Rudy in fact our anticipated use of the spline is for the Hurricane it is to fit the prop shaft on the merlin.
Yes Jack is very much involved in the mosquito project.
How was your luck trying to get an OEM take off part abroad? Didn't they make like 8000 mosquito's, most with Merlin engines, surely there must be some parts left over in the UK/Europe? Or are they one of those unobtanium type of parts ? Or just prohibitively expensive?
That's kind of why I asked the question in post #19. I'm going to guess a prop shaft component is a somewhat precision component with specific tolerances & material specs. Not saying someone on the forum could not replicate, but I think a lot more information is required. Do you at least have a picture? Does it engage the highlighted area like attached sketch? You don't need to answer here if you have private leads, but I'm just personally curious.
Attachments
Hmmm.... 2mm endmill?
All that we know so far is the splines are approx. 0.25" wide, 0.125" deep in a 3" ID. No indication as to how long the splines are or how many.
Note that he is looking for internal splines not external splines.
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Gary told me the splined hub is to go into a “test club” propeller for engine run in a test stand on the ground. So no, it will not go flying.
The splined hub will go inside the prop and mate to the prop shaft of the engine. Most props are made from aluminum. Test props are made from wood for safety’s sake. Hub material will still most likely be alu. Gary can confirm.
We don’t yet have the details of the prop and/or the prop shaft of the merlin engine.
Gary will get back to us. Or one of us will go measure / inspect the parts they have to see what is involved.
Here is a test prop mounted to an engine on a test stand - that is what they are trying to do.
they have the engine, and the prop, the two just don‘t fit together yet. That is where they need our help: to make the interface hub between the two items.
I think someone needs to find out what an original is hub made from I don't think aluminum would cut it, Merlin's have like 1500ftlbs+ of torque, even with that test prop it's still going to catch a lot of wind, and it looks very heavy, I could see it shearing the splines right out of an aluminim hub in about 10 seconds