My 5hp Robin Build

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cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
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Colonial Coast USA.
Just a heads up on the 5/8 bottom bracket. I went ahead and drilled my cranks to 5/8. The shaft is a good hammer fit. I am going to weld the right side crank in place, then drill and tap the left crank and shaft for for a set bolt. I can easily remove shaft later for bearing replacement using this method. Crank drilling, at least mine required a drill press. If all are similar to mine hand drilling would be asking for a broken wrist.
 
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midwestmayhem

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Dec 23, 2011
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cannonball2 said:
Just a heads up on the 5/8 bottom bracket. I went ahead and drilled my cranks to 5/8. The shaft is a good hammer fit. I am going to weld the right side crank in place, then drill and tap the left crank and shaft for for a set bolt. I can easily remove shaft later for bearing replacement using this method. Crank drilling, at least mine required a drill press. If all are similar to mine hand drilling would be asking for a broken wrist.
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Ya thats pretty much what I planned on doing except that I plan on trying to cut keyways and drill and tap for set screws in both. The keyway on one crank will have to be 180 degrees from the keyway in the other, so when I get done the crank arms will be in thier correct positions. Hopefully with the help of the keyways and keys, the both arms will stay in thier correct positions and not twist on the shaft.
 
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midwestmayhem

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Dec 23, 2011
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BigBlue said:
Midwesternmayhem,

I don't know how you're going to cut your keyways, but I found this YouTube video the other day on how to make a jig to cut keyways on a lathe. I'll be following your post to see how the crank arms come out.

http://www.youtube.com/watch?v=eVgZol6Mfvo

Good Luck,

Chris
AKA: BigBlue
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cool vid, tho it shows cutting a keyway into a shaft and not into a hole like I'll be doing with the crank arms. I wish I still had access to the lathe. Once I'm done the crank spindle will be a 5/8 keyed shaft. I'll probably use a file to cut the keyways into the crank arms. I hoping to get started soon, job has me pretty well busy right now.



landuse said:
Where do you rest your feet? I don't see any pegs anywhere.

Nice build by the way
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The couple of times I rode it I just held up my feet, there were no pegs or rests.laff When I get done re-building the drive system I'll be able to use the pedals
 
MEASURE TWICE

MEASURE TWICE

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Jul 13, 2010
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Something was said about bearing blocks. I'm not sure if that is a like what I had a bit of a problem with the pillow bearing holders as I call them or collars.

They were the things that I put onto the jackshaft to keep the pillow bearings at each end pushed up against the pillow bearing holder end stops that hold the jackshaft. Without these or a pulley right up against the pillow bearings at their end in the stops, the whole jackshaft would not stay in place.

I originally bought the kind that have no keyway but do have a set screw. The screw marks up the jackshaft making changes hard to do. The scratches on the jack shaft even if not in the keyway (which do leave a nearly completely ruined jackshaft keyway) make moving pulleys sideway on and off a bear. Once I last cleaned up the jackshaft with emory cloth I had to do better.

I found these ones that have option for ones with keyways but without set screws that push on the jackshaft. I suppose the keyway allows for a long length key to continue through and on to an area of the jackshaft where there are pulleys that use keyways and set screws.

Here is the good part. There is maybe what you call a set screw, but it does not go anywhere except at a tangent to the jackshaft and pull a split collar together that otherwise is just a few thousandth of an inch larger without tightening down yet on the set screw. Lock-tite could be put on that set screw.

There are but even more expensive collars that have two of these screws, but come apart in halves. I did not see the need for that unless you really have to minimize time making changes so that the way they come off the jackshaft without the need to slide it off either end.

You can find them at Enco or many other places like Fastenal and Grainger ect. At Enco where I got free shipping when my order was over 25 dollars, but that was then and a promotion. Last I hear it was 100 dollars. The single split collars without keyways were around 7 dollars each as opposed to 3 dollars for the kind that scratch the jackshaft, but no longer a headache so I have a few left over for extra projects.

They are in NV and I'm in CA and so I got the free shipping at the slowest rate, but parts arrived next evening:)

http://www.use-enco.com/CGI/INSRIT?PMAKA=990-3537

5/8 ID,1 5/16 OD,7/16W CLIMAX 1PC CLAMP COLLAR
 
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midwestmayhem

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Dec 23, 2011
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I got a 5/8 drill bit and have been drilling holes in scrap to see how well the 5/8 shaft will fit. I kept having problems with tri-lobed holes, star shaped holes, and tapered holes. Tryed a different bit, tryed diffent speeds, and tryed cutting lube with no better results. I think the problem is with the quill tube, as soon as you start lowering it down, it gets alot of slop. There's an set screw on the side that rides in a grove on the quill that's suppose to be for adjustment. But it seems the grove isn't cut parrell to the quill, causing little to no quill movement when the quill is all the way up and a lot of movement as it is lowered.

I think I'll try a 9/16 bit and dremel from there. The way this press is acting, after I drill the 9/16 hole it should be closer to 5/8 anyway.
 
cannonball2

cannonball2

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Oct 28, 2010
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If you are using a drill press, you must use a vise and clamp it firmly to the table, which needs to be firmly locked also. My bit a Hanson I believe, drilled the perfect size hole. Its a tricky drill job due to the fact you are drilling out a tapered square hole. The bit wants to grab like crazy!
 
wayne z

wayne z

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Dec 5, 2010
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midwestmayhem said:
I got a 5/8 drill bit and have been drilling holes in scrap to see how well the 5/8 shaft will fit. I kept having problems with tri-lobed holes, star shaped holes, and tapered holes. Tryed a different bit, tryed diffent speeds, and tryed cutting lube with no better results. I think the problem is with the quill tube, as soon as you start lowering it down, it gets alot of slop. There's an set screw on the side that rides in a grove on the quill that's suppose to be for adjustment. But it seems the grove isn't cut parrell to the quill, causing little to no quill movement when the quill is all the way up and a lot of movement as it is lowered.

I think I'll try a 9/16 bit and dremel from there. The way this press is acting, after I drill the 9/16 hole it should be closer to 5/8 anyway.
Click to expand...
How thick is the scrap that you're drilling in? If you're getting tri- shaped holes, it must be sorta thin and you're not using several different sizes of pilot bits.

A sure way of drilling a round hole thru a square one ,on a sloppy drill press is to make a drill guide jig.
Just take a piece of scrap steel at least 1/2" thick, firmly clamp or tackweld it over the square hole. You could drill the scrap to whatever size bit that closely fits the stock crank hole, and then use that bit to center the jig with the crank hole before securing them together.

Mount it very solidly in the drill vise, with the steel on top, then drill thru the steel and crank arm at once. Don't try to drill out all the meat at once,use several bits to gradualy bore it to the finished size.

If the 5/8" bit is drilling a few thousands too large, just carefully lightly dress the sides of the bit some against the sides of the bench grinder wheel, and try another test hole in thick scrap, using succesive sized pilot holes.

The thick steel guide right against the crank hole will keep the bit from wandering, no matter how sloppy the quill.
 
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midwestmayhem

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Dec 23, 2011
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southeast S.D.
cannonball2 said:
If you are using a drill press, you must use a vise and clamp it firmly to the table, which needs to be firmly locked also. My bit a Hanson I believe, drilled the perfect size hole. Its a tricky drill job due to the fact you are drilling out a tapered square hole. The bit wants to grab like crazy!
Click to expand...
The scrap is secured to the press via a vise that is bolted onto the table of the press which was locked in.



wayne z said:
How thick is the scrap that you're drilling in? If you're getting tri- shaped holes, it must be sorta thin and you're not using several different sizes of pilot bits.

A sure way of drilling a round hole thru a square one ,on a sloppy drill press is to make a drill guide jig.
Just take a piece of scrap steel at least 1/2" thick, firmly clamp or tackweld it over the square hole. You could drill the scrap to whatever size bit that closely fits the stock crank hole, and then use that bit to center the jig with the crank hole before securing them together.

Mount it very solidly in the drill vise, with the steel on top, then drill thru the steel and crank arm at once. Don't try to drill out all the meat at once,use several bits to gradualy bore it to the finished size.

If the 5/8" bit is drilling a few thousands too large, just carefully lightly dress the sides of the bit some against the sides of the bench grinder wheel, and try another test hole in thick scrap, using succesive sized pilot holes.

The thick steel guide right against the crank hole will keep the bit from wandering, no matter how sloppy the quill.
Click to expand...
Scrap is 1/4 thick. I tried drilling through two layers clamped together and got the same result. I have trying to start with a 1/4 bit, then 1/2, then 5/8. Thanks for the ideas about the jig and dressing the bit. Earlyer today I slid a 5/8 down the drill bit from shank to tip and I noticed it starter binding about an inch from the tip. I dressed it down just untill the hub slid down it smoothly, I'll try it tomorrow. I got a 9/16 bit with seems to help some, and I also went through the press and it seems to be working a little better.
 
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midwestmayhem

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Dec 23, 2011
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Update- I had to dress down the drill bit a little more, it's an Irwin bit just in case anyone was wondering. I have a tight fit know, shaft has to be hammered in. I'll be finding some scrap to use as guides, thanks again wayne for the advise

Cannonball2-When you got done drilling the 5/8 hole, where the corners of the square taper still visible? I'm wondering cause if they are, they would make a great mark for me when I go to cut the keyways. If not, I'l just mark them before I start drilling. I guess if nothing else I can mark them before just in case.
 
cannonball2

cannonball2

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Oct 28, 2010
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Colonial Coast USA.
Yeah there were traces of the taper still visable. Just file your keyways 180 apart. I used the key way on the shaft for alignment on my crank as the rt side is welded, just aligned the cranks 180 to the key way. I you have access to a welder weld one side and you willl only have to file one key way.
 
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midwestmayhem

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Dec 23, 2011
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southeast S.D.
cannonball2 said:
Yeah there were traces of the taper still visable. Just file your keyways 180 apart. I used the key way on the shaft for alignment on my crank as the rt side is welded, just aligned the cranks 180 to the key way. I you have access to a welder weld one side and you willl only have to file one key way.
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Thanks, I thought I mentioned the keyway thing before, nice to be reminded though, it would suck to mess that up.:) I have an 220v stick and a 110 wire feed, but I'll probably still key both, just in case I need to make and adjustments latter.
 
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