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bpimm

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#1
Working up a project for my Dad, His hobby has been wood boats, His/our first boat was a Keeler craft 16' lapstrake bought in 1965, it was a 1961 boat so I was 4 years old when we bought it, We still have it, in fact my brother and I are just finishing up it's third restoration. Actually his first boat was a folding canoe that he built when he was about 12, it was about 6 feet long and folded in half, had wheels he hooked on it and he towed it behind his bike down to the local slough to paddle around. He has since built /restored several wooden boats including strip built kayaks that he loves to go paddling in, unfortunately at 80 his hands aren't what they used to be, due to a chipper accident his right hand has only the thumb and forefinger left and the arthritis has left it pretty non functional and the left has arthritis as well plus there is the non repairable rotator cuff, you get the idea, so paddling has become very difficult.

Our solution is to build an outboard motor for the kayak so he can still enjoy getting out on the water, this is a 3 generation project with my son involved with the motor and controls as well.

What I have designed is a three piece aluminum housing that threads together, I'll include drawings with the post, I found a "high efficiency" prop form a company that makes electric Kayak motors, imagine that, so we could just buy the whole thing for a little over 2 grand but where's the fun in that right?.

I have the design pretty close but where I'm having issues is figuring out the work flow, 2 of the parts need to be machined from both ends and stay concentric and the parts have to thread together and stay in alignment.

I have a pretty good lathe, I think, but I only have a 3 jaw chuck so if I flip the part it wont run true and what I have to turn from the other end is the other bearing pocket and the attachment threads so even a few thou could be a problem for alignment. I do have a 5C collet chuck but that only gets me to 1" and the material I'll be working with is 3" and all the turning is ID turning so I don't think turning between centers would work plus I don't have mandrels or dogs. I do have a small cnc mill, Grizzly round column drill/mill but I don't think the accuracy is very good, it's pretty worn and has some vibration issues. I also have a decent manual knee mill although my tooling is limited for all the machines. Oh I do have a 4 jaw chuck on my first lathe but it is a well used 1905 Seneca Falls star lathe, not going to provide the accuracy needed.

My background is not machining, I started out in the electronics industry, followed by running heavy construction equipment for a bunch of years, The Seneca falls lathe came first as a gift... "Get it out of here or it's going to the dump" I worked on it and got it running and fell in love with making chips so I bought the cnc mill to play with and quickly found it's limits. The bigger lathe and mill came along when I wasn't even thinking of new equipment but a friend of my brother's was selling his family's equipment, they hadn't used it in about 20 years and he was trying to clear out some space so I bought them.

Here is a screen capture of the assembly in Fusion 360 for reference.
Motor Assembly.JPG
There are 4 components in the body in this view, the nose cone which threads into the center section which the motor mounts in, then the tail housing has the prop shaft, bearings and seal and threads into the center section using a small love joy type coupler to hook to the motor. This view also has the prop hub modeled on the back.

Here's my thought process for work flow hopefully you guys can point out the holes in my thinking and maybe fill some of them as well.
Start by making the thread gauges for the 2.375 X 20 LH threads, then start the center section and cut the back side where it mounts to the tail section, get the internals finished on that end. Follow that with starting the front side of the tail section and do everything on that side then screw the center section on to it and finish the front side of the center section while mounted to the tail section that's still in the chuck. At this point I could rough down the outside of the center section.
Then make a blank female thread so I could thread the tail section into it and finish the back side of the tail section and rough down the OD.
Next I would rough out the nose cone inside and threads, probably do the strait bore as well.
Then put the nose cone in the cnc mill and let it contour the inside of the cone.
Now move the female thread blank into the cnc mill, mount the tail section and let the cnc cut the outside profile on the tail section followed by the outside profile of the nose cone. at this point all the parts should be roughed out and I would need to do a male thread blank in the lathe so I could mount the center housing and tail section to finish the outside, hopefully just a bit of filing and sanding/polishing, followed by mounting the center section and nosecone for the finishing process.

I chose left hand threads because the rotation of the mill cutter will be tightening the part as it cuts the outside profiles so I'll have to flip my lathe tooling or work on the back side with the lathe running backwards to get the same tightening effect, I figure that is easier than reversing the direction of the mill and getting LH cutters for it.

I have included drawings of the parts in pdf and dwg format and a screen capture of the tail section because the drawing didn't pick up the hidden lines on the inside like it did on the other 2 and I haven't figured out why yet.

This is the most ambitious machining project I have come up with yet, am I nuts for trying this? any and all suggestions are welcome including the "What the H*** are you thinking type" LOL.

I'm sure I left out some needed information so please don't hesitate to call me on what's missing.

Thanks
Brian
 

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RJSakowski

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#2
Working up a project for my Dad, His hobby has been wood boats, His/our first boat was a Keeler craft 16' lapstrake bought in 1965, it was a 1961 boat so I was 4 years old when we bought it, We still have it, in fact my brother and I are just finishing up it's third restoration. Actually his first boat was a folding canoe that he built when he was about 12, it was about 6 feet long and folded in half, had wheels he hooked on it and he towed it behind his bike down to the local slough to paddle around. He has since built /restored several wooden boats including strip built kayaks that he loves to go paddling in, unfortunately at 80 his hands aren't what they used to be, due to a chipper accident his right hand has only the thumb and forefinger left and the arthritis has left it pretty non functional and the left has arthritis as well plus there is the non repairable rotator cuff, you get the idea, so paddling has become very difficult.

Our solution is to build an outboard motor for the kayak so he can still enjoy getting out on the water, this is a 3 generation project with my son involved with the motor and controls as well.

What I have designed is a three piece aluminum housing that threads together, I'll include drawings with the post, I found a "high efficiency" prop form a company that makes electric Kayak motors, imagine that, so we could just buy the whole thing for a little over 2 grand but where's the fun in that right?.

I have the design pretty close but where I'm having issues is figuring out the work flow, 2 of the parts need to be machined from both ends and stay concentric and the parts have to thread together and stay in alignment.

I have a pretty good lathe, I think, but I only have a 3 jaw chuck so if I flip the part it wont run true and what I have to turn from the other end is the other bearing pocket and the attachment threads so even a few thou could be a problem for alignment. I do have a 5C collet chuck but that only gets me to 1" and the material I'll be working with is 3" and all the turning is ID turning so I don't think turning between centers would work plus I don't have mandrels or dogs. I do have a small cnc mill, Grizzly round column drill/mill but I don't think the accuracy is very good, it's pretty worn and has some vibration issues. I also have a decent manual knee mill although my tooling is limited for all the machines. Oh I do have a 4 jaw chuck on my first lathe but it is a well used 1905 Seneca Falls star lathe, not going to provide the accuracy needed.

My background is not machining, I started out in the electronics industry, followed by running heavy construction equipment for a bunch of years, The Seneca falls lathe came first as a gift... "Get it out of here or it's going to the dump" I worked on it and got it running and fell in love with making chips so I bought the cnc mill to play with and quickly found it's limits. The bigger lathe and mill came along when I wasn't even thinking of new equipment but a friend of my brother's was selling his family's equipment, they hadn't used it in about 20 years and he was trying to clear out some space so I bought them.

Here is a screen capture of the assembly in Fusion 360 for reference.
View attachment 268969
There are 4 components in the body in this view, the nose cone which threads into the center section which the motor mounts in, then the tail housing has the prop shaft, bearings and seal and threads into the center section using a small love joy type coupler to hook to the motor. This view also has the prop hub modeled on the back.

Here's my thought process for work flow hopefully you guys can point out the holes in my thinking and maybe fill some of them as well.
Start by making the thread gauges for the 2.375 X 20 LH threads, then start the center section and cut the back side where it mounts to the tail section, get the internals finished on that end. Follow that with starting the front side of the tail section and do everything on that side then screw the center section on to it and finish the front side of the center section while mounted to the tail section that's still in the chuck. At this point I could rough down the outside of the center section.
Then make a blank female thread so I could thread the tail section into it and finish the back side of the tail section and rough down the OD.
Next I would rough out the nose cone inside and threads, probably do the strait bore as well.
Then put the nose cone in the cnc mill and let it contour the inside of the cone.
Now move the female thread blank into the cnc mill, mount the tail section and let the cnc cut the outside profile on the tail section followed by the outside profile of the nose cone. at this point all the parts should be roughed out and I would need to do a male thread blank in the lathe so I could mount the center housing and tail section to finish the outside, hopefully just a bit of filing and sanding/polishing, followed by mounting the center section and nosecone for the finishing process.

I chose left hand threads because the rotation of the mill cutter will be tightening the part as it cuts the outside profiles so I'll have to flip my lathe tooling or work on the back side with the lathe running backwards to get the same tightening effect, I figure that is easier than reversing the direction of the mill and getting LH cutters for it.

I have included drawings of the parts in pdf and dwg format and a screen capture of the tail section because the drawing didn't pick up the hidden lines on the inside like it did on the other 2 and I haven't figured out why yet.

This is the most ambitious machining project I have come up with yet, am I nuts for trying this? any and all suggestions are welcome including the "What the H*** are you thinking type" LOL.

I'm sure I left out some needed information so please don't hesitate to call me on what's missing.

Thanks
Brian
An ambitious project indeed! What size lathe? At 3" O.D. I would want more than 1/2" to 3/4" jaw grip.

For a custom thread, yes, I would make the thread gages first. I would then turn the middle section internals, including thread from one end. Next turn the tail piece internals leaving the O.D.. While the tail piece is still in the chuck, thread the center section on and turn the remaining internals.
Remove the work and replace with the nose piece stock and turn the internals.. Thread the center section and tail piece on and turn the exterior. All that remains is to turn the exterior of the nose piece. Remove the tail piece and mount the center section, back end first. Shim chuck jaws as necessary to have it run true. Screw on the nose piece and turn O.D. Since this is just an aesthetic surface, aq slight runout could be tolerated. Blend in any imperfections with file and emery cloth.
 

RJSakowski

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#3
I friend of mine has a pedal kayak outfitted for fishing. It drives a prop. I forget what the top speed is but it was impressive. A much simpler design and build if your Dad's legs are still functional.
 

RJSakowski

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#4
If you haven't considered it yet, a pulse width modulated speed control greatly extends battery life. I'm still using one that I built over 30 years ago on my trolling motor. I have infinite control from about 30 rpm to max.
 

bpimm

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An ambitious project indeed! What size lathe? At 3" O.D. I would want more than 1/2" to 3/4" jaw grip.

For a custom thread, yes, I would make the thread gages first. I would then turn the middle section internals, including thread from one end. Next turn the tail piece internals leaving the O.D.. While the tail piece is still in the chuck, thread the center section on and turn the remaining internals.
Remove the work and replace with the nose piece stock and turn the internals.. Thread the center section and tail piece on and turn the exterior. All that remains is to turn the exterior of the nose piece. Remove the tail piece and mount the center section, back end first. Shim chuck jaws as necessary to have it run true. Screw on the nose piece and turn O.D. Since this is just an aesthetic surface, aq slight runout could be tolerated. Blend in any imperfections with file and emery cloth.
It's a Jet 1440 lathe from years ago when they got them from URPE in Spain.

I like that, it cuts down making the blanks, but my confidence for turning the ellipse freehand is zilch. That's why I was going to let the cnc do that LOL. I could still follow your process and use the center section in the mill to cut the nose and tail shapes, or just the nose and if I made the thread gauge right I could chuck it back up to put the final polish on the parts. P1010088.JPG
 

bpimm

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#6
I friend of mine has a pedal kayak outfitted for fishing. It drives a prop. I forget what the top speed is but it was impressive. A much simpler design and build if your Dad's legs are still functional.
1 knee replaced and the other needing it... Also hard to retrofit a strip built kayak. IMG_2338.jpg
It's going on the one on the right, the one on the left he built for mom. That pic is out the back of the Houseboat he built. He likes to cruise around in the houseboat and paddle from it as a base.
 

bpimm

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#7
If you haven't considered it yet, a pulse width modulated speed control greatly extends battery life. I'm still using one that I built over 30 years ago on my trolling motor. I have infinite control from about 30 rpm to max.
Definitely PWM with the advent of the 4 motor drones there are really good motors and controllers available really inexpensively.
 

rock_breaker

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#8
Impressive craftsmanship. Making the parts on your lathe in my mind is do-able with perhaps light cuts and careful chuck mounting. Your plan sounds reasonable, obviously minimizing the "re-chucking" is imperative. Good luck.
Ray
 

bpimm

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#9
Ok first step done. I can cut left hand threads.....

IMG_20180621_100638788.jpg IMG_20180621_100658804.jpg

Got the male thread on the first try but it took 2 trys to get the female, something about boring it to the major diameter then threading.. was a little loose fitting..

I'll use the female gauge as the holder in the cnc mill, if I had a 4 jaw for the lathe I'd use it there as well.
 

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#10
Thread gages of the same nominal size should never fit together (straight threads; taper threads are another story). Not to sidetrack your build thread, just something you should know. Not worth another thread to itself. Seems we have already discussed it somewhere anyway.
 

bpimm

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#11
I've read that. At this point I feel good to get threads to work together period. I doubt I could make a thread gauge to tight enough tolerances to work with anyone else's threads so I'm happy with having the two parts screw together. lol
 

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#12
You stated "something about boring it to the major diameter then threading.. was a little loose fitting.. ". Shouldn't you be boring to the MINOR diameter then threading? Then the grooves cut by threading would give you the major diameter.
 

bpimm

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#13
You stated "something about boring it to the major diameter then threading.. was a little loose fitting.. ". Shouldn't you be boring to the MINOR diameter then threading? Then the grooves cut by threading would give you the major diameter.
Yep, I looked at my notes and read the wrong number, was really happy when I hit the bore dead on, cut the threads and wtf then I realized what I had done. more scrap in the bin...
 

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#14
Nice lathe , great family project too. We're waiting for updates already , threading looks good on both pieces pictured.
 

bpimm

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#15
Thought I'd post some progress pics, I've got most of the internal turning done, here are the three pieces starting with the inside of the nose cone.
IMG_20180628_175856036.jpg
The center section.
IMG_20180628_175914068.jpg
the tail section with 1 bearing pocket cut,
IMG_20180628_175933770.jpg
all three
IMG_20180628_180010576.jpg
and screwed together.
IMG_20180628_175844220.jpg
I drilled some weight reduction holes inside the tail section.
IMG_20180704_150734046_HDR.jpg
Today the nose cone is slowly appearing on the mill.
IMG_20180704_113242704.jpg IMG_20180704_135824595.jpg IMG_20180704_145828431.jpg
When the nose cone is done the tail section goes in the mill for it's external shaping.

Brian
 

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bpimm

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#16
Nosecone is off of the mill.
IMG_20180704_161321110.jpg
IMG_20180704_161324295.jpg
I also drilled the motor mount bolt pattern,
IMG_20180704_161737129.jpg
Motor mounted.
IMG_20180704_161730555.jpg
Tail housing is on the mill now. Starting to get excited...
 

brino

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#17
Wow!
It sure does NOT look like you're in over your head!

Great progress on an ambitious project.
Your hard work is paying off.

...and thanks for sharing it with us.

-brino
 

bpimm

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#18
Wow!
It sure does NOT look like you're in over your head!

Great progress on an ambitious project.
Your hard work is paying off.

...and thanks for sharing it with us.

-brino
Honest, I've never made anything this complex, and I did have to make 2 of the center sections.... the first one ended up with RH threads on one end... I just couldn't get the threads to start. I kept taking another .001 off and after I was .010 -.015 over size by the dials I figured it out. lol.

I am very happy with how it's coming out, surprised too.
 

bpimm

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#19
Tail section just came off the mill, now for some cleanup. IMG_20180704_201316521.jpg
all together.
IMG_20180704_201347537.jpg
Back to the lathe tomorrow.
 

bpimm

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#20
Turned the center section down to match the ends and sanded it down to 400 grit, how fine do I have to sand aluminum to get a good polish?

IMG_20180705_092958762.jpg
 

rock_breaker

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#21
Not sure about the sanding but sure admire your work.
Ray
 

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#22
probably 800 grit or more then polish with a polishing compound. Check youtube there are lots of videos on polishing aluminum. B y the way, great job.
 

bpimm

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#23
Thanks for the compliments guys, my confidence is growing with this project.

I'm using 6mm stainless rod for the prop shaft, both the motor and the prop are 6mm, I couldn't find a seal for 6mm so I got a 11mm seal and some 11mm stainless rod thinking I would make a spacer / bushing between the prop and outer bearing, this would give me a boss for the seal and put the thrust load on the bearing directly, I'm thinking of using Loctite 609 to hold the bushing on to the 6mm shaft. Will it need any kind of mechanical connection as well? Is there a better product for attaching and waterproofing the joint?

This will be my first time working with stainless so any pointers for drilling and boring the bushing true would be great. I don't have any metric drill bits or reamers, but I do have a tiny HSS boring tool that came in something I bought, it has worked well on steel and aluminum in the past and I'm hoping it can do the final bore in the stainless.

I tried to go over the 400 grit with 1000 grit and polish but the 1K didn't get all the 400 scratches out, I didn't think it would but I had it. I'll get some 600, 800 and 1200 to play with and see how polished I can get it...

I'm going to make a fiberglass cast of the tail section of the Kayak to mount the motor on so that will be coming up soon, I want to have this thing ready test even if it's just a prototype of the mount by the first weekend in August, we're taking 3 boats and the 2 Kayaks to a local wooden boat festival for the weekend.
 

mattthemuppet2

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#24
cool project! For polishing aluminium, I use 320->400->800->1000->1200->1500->2000->2500 then use Mothers Mag wheel polish and some tissue. That'll get you to a mirror finish and the polish offers some degree of protection. Make sure to use wet'n'dry sand paper and keep the paper wet. Otherwise it'll load up and scratch the work.
 

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cool project! For polishing aluminium, I use 320->400->800->1000->1200->1500->2000->2500 then use Mothers Mag wheel polish and some tissue. That'll get you to a mirror finish and the polish offers some degree of protection. Make sure to use wet'n'dry sand paper and keep the paper wet. Otherwise it'll load up and scratch the work.
Just keep the sanding crap off the ways of the lathe--I use a big piece of heavy cardboard cut to size when I do thi.
 

bpimm

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#26
I put the prop shaft together this morning, drilled and bored the 11mm stainless, only took 3 tries to get it right... the rest was pretty strait forward, run a die over the end to thread it and drill a cross hole for the drive pin for the prop.

here is the motor mounted with the lovejoy coupler installed
IMG_20180711_091030418.jpg
IMG_20180711_091035787.jpg
the tail section with the bearings and seal in place.
IMG_20180711_091046788.jpg
IMG_20180711_091050811.jpg
shaft in.
IMG_20180711_091150356.jpg
Prop installed.
IMG_20180711_091243811.jpg
Motor on, it goes together really easy.
IMG_20180711_091308830.jpg
The wires will come out through a hole into the shaft coming down to the motor from the boat then the nose cone can go back on.
I got a foot of aero tube for the shaft,
IMG_20180711_091419918.jpg
IMG_20180711_091430289(1).jpg
I don't have a TIG welder so I'm going to build a jig to hold it all together and take it to someone to weld the shaft and scag on.

I'm also working on the mounting bracket for the back of the Kayak so that's coming up soon.

I'm off to get more sandpaper so I can finish the polishing and drill the holes for the wires and pin wrench.

Thanks for all the encouraging words.
 

savarin

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#27
For polishing aluminium use the grades of papers Matthemuppet stated, I use wet-n-dry papers and lubricate it well with WD40.
Followed with tripoli then rouge.
This will bring up a brilliant diamond like shine, then a coat of car wax polish as a bit of protection.
 

bpimm

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#28
Here's what I came up with for the mounting bracketry to hang the motor on the back of the Kayak. First off the Kayak will get a fiberglass cast made of the back tip of the boat that will pin onto it via a hole that is already on the Kayak then this bracket setup will mount to that form fitted cast, In theory. The cast piece will have a 1/4" thick strip along the rear for the bracket to bolt to.

The first bracket that bolts to the Kayak
Boat Bracket.JPG
This is followed up with what I call the lift bracket because the motor needs to be able to tilt up for shallow water, beach landings or hitting debris in the water.
Lift Bracket.JPG
Then the rudder bracket that allows the rudder to pivot
Rudder Bracket.JPG
Then all assembled.
Rudder Bracket V2.JPG
And after making some chips.
IMG_20180724_155100282.jpg
IMG_20180724_155107641.jpg
IMG_20180724_155146932.jpg

That's where I'm leaving off today, I need to finish sanding and polishing the motor housing and the aero tube and get it all welded together.

I need to find a good TIG welder in the local area that can make some pretty welds so I don't have to sand and polish out the welds, I know that's not me!
 

Mitch Alsup

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#29
I don't think you are in over your head at all..........
 

brino

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#30
Brilliant!
-brino
 
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