Need some input on this build and a machinist recommendation

[Randybee1]

Hey guys, I have a 3 cyl Kubota (D905D) mounted to a 5 kw Onan generator. I bought the whole shebang for $250.00. It has all the bells and whistles - radiator, 240/120 outlets, temp gauge, oil pressure gauge etc, and its on a cart! It starts up and purrs like a kitten. The head is a 1800 rpm direct drive unit. The head is toast so my intentions were to take it off and put on a ST head via a Lovejoy coupler. Upon taking off the generator head I found that it was attached to the engine with a piece of thin sheat metal. Here is a picture of the flywheel end with the sheat metal next to it. The round disc was mounted to the flywheel and the gen head was bolted to the center.



Here is a picture of the rotor shaft. It has the coupler on it that bolts to the sheatmetal disc. It appears to be a press fit.



So, my original idea is not going to work. I was thinking of having someone machine a stub shaft for me to bolt onto the flywheel, then mount the ST head via a couple.

2 questions:

1) Does anyone have a better idea? if so, what?
2) can anyone recommend a machinist? I like the work Mike Montieth did but I've been lead to believe he no longer is "in the business"

Randy B

[Randybee1]

Don't know why the first pic did not come out so here it is again..

[cohippy]

here is what i had made to couple a TK Isuzu C201 to a 24Kw ST head
http://postimage.org/image/47jt5ofo9/

[Thob]

What you have is called a single bearing generator.  You can either have it rewound at a motor repair shop or buy a whole new unit.  Central Georgia Generator carries units that will fit:

http://www.centralgagenerator.com/

If you already have an ST unit, then yes, a stub shaft can be machined (perhaps purchased?) and then connected up with a belt drive.  You don't want the pulley to be away from the flywheel any more than necessary as the side loads from belt tension can ruin the engine's bearing.

If you don't already have an ST unit, then a good quality brushless generator from cgg will probably cost less than the stub shaft and pulleys and an ST unit.

[Randybee1]

Thob, the original set up was a direct drive. I already have a 7.5 KW ST head that I plan to put on it. I was planning to use a stub shaft and connect the two units togther with a Lovejoy coupler. Just looking for suggestions.

[mobile_bob]

use your existing flexplate as a template, to make up another perhaps a half inch thick

have it trued up on its outside diameter, so it fits the flywheel properly, and also have it machined/bored so that a love joy half can be welded to the inner bore of the flexplate.

then attach this newly minted and not very flexible flexplate to the flywheel and couple the st head via the complimentary lovejoy half and spider of choice.

you should be able to take your flexplate and measure it so that a steel shop can flame cut or one of the other more fancy cutting methods, cut out the half inch plate... take that blank and the flexplate to a machine shop along with the love joy half so they can bore the plate to fit the lovejoy, and then turn the outside to the same dimension of the original flexplate... you then can either have them bore the 6 mounting holes or do them yourself using the original plate for a template to place those holes.

if you can get a plasma cutter to cut the blank they can get it very close to a finished product, which of course reduces the time required for the machinist to finish it on his lathe and reduce the finished cost of the part.

if you have access to a laser cutter, they can the thing cut to a gnat's hair of perfection
which likely will result in no further machining required...  if you have them cut the OD a few thousands over and also have the lovejoy half the same id as the st head shaft, you can then mount the welded assy to the st head and using an angle grinder finish grind the OD of the plate to near right on with very little effort.  just put it on the st head and use the st shaft as a spinning arbor while the angle grinder will remove the needed few thousands while spinning the flexplate.  all you would really need is a basic steady rest to support the grinder, something like  a cement block would work fine.

while it would be nice to have it machined to less than a thousands of an inch, that is not really necessary, the spider will absorb a few thousands or runout without issues, because the st is a 2 brg head it needs no support from the plate.

there are some options for you.
fwiw
bob g

[mobile_bob]

here is another option that if i were you i would seriously consider

make up the new half inch plate as formerly described

instead of welding in the lovejoy half, get one of those taper lock weld in hubs
they are very commonly available at farm ag stores and of course the gear/brg suppliers as well

they have a machined step so that you can fit them into your new plate and weld them  in and get them straight without a lot of fuss

then insert a shaft to install your lovejoy half onto...

the advantage here is you can make the shaft long enough to also include room for a single or double groove drive pulley to be used for an alternator or waterpump, or refer compressor or whatever.

the question of trapping the belt can be taken care of by either the use of AA hexagonal section belts that can be used in a serpentine application, this allows the belt to lay over the drive pulley and around an alternator on on side and a compressor on the other side with an idler above the drive pulley... this makes changing the drive belt(s) something that would take not more than a minute or two if the alternator swivel is done right.

my thinking is to always provide all the options possible when i set out to build something new or modify something for another use... this added capability could be done very easily and would only add the additional cost of a taper lock weld in hub and a piece of stub shaft, and of course the new pulley. the pulley could be put off till a later time, just make the shaft long enough to accommodate one later as needed.

one final thought is if you decided to go with a single groove pulley, you could go with a standard A or B section belt, and be able to replace it by sliding back the drive half of the lovejoy on the stub shaft and sliding forward the driven half of the lovejoy on the gen shaft,,, this ought to provide enough room to slip the belt(s) out, but will take much more time and might be a problem when down the road the lovejoys rust into position...

if it were me i would seriously consider doing this option,  and i would seriously consider the use of AA hexagonal section belts... they can be gotten off ebay for very reasonable costs. they also seem to run much cooler than A section belts, and i am not sure why this is, but they do.

just wanted to add this

bob g

[Randybee1]

Bob, Thanks for all of the suggestions... but now I have too many options..
This will be a direct drive set up, no pulleys. I like the idea of the taper lock weld in hub. I'll look into that this evening.

Randy B

[mobile_bob]

i know this is to be a direct drive st head, i only suggest putting in a longer stub shaft so that a pulley can me mounted between the engine and the st head... between the taper lock hub and the drive half of the lovejoy...

having that pulley in there, or the ability to put on in later would open up a lot of options down the road, should you decide to put an alternator, or a pump, compressor or whatever on the setup.

basically don't paint yourself into a corner, leave your options open by using a longer stub shaft.  if you mount the st head too close and use a short stub shaft, you are locked in and then later should you decide to add optional driven components you won't be able to do so without reworking the st mount and moving it further away.

just a thought anyway.

additional thought
find out what the st head drive shaft size is?  38mm from memory but i might be wrong?  but lets assume that is what it is

assuming a 38mm size, buy a 38mm taper lock hub and and a 38mm stub shaft and 38mm lovejoy halves.

then when you assemble the two shaft should line up to where one lovejoy half can slide right off the drive stub and right onto the generator shaft... if you then assemble so that one of the halves not only fits on one shaft but extends a bit over the other shaft you will have then provided a lot of additional side thrust support for the pulley should you ever decide to use one.

i hope you follow what i am talking about, if you would like i can draw up a sketch in paint and post it?

its just that you have such a cool setup, and having the ability to incorporate other driven parts in my opinion would be very desirable.

fwiw
bob g

[uber39]

way to go Bob,
        love it when people think outside the box, and in such a simple way. That way of coupling would make life so much easier in so many ways
            Ian

[Randybee1]

Bob, I like the idea of the "extra" pulley added. I also am a firm believer for building with the future in mind. I have visited 3 different Amish farm generator sheds and am always amazed that they typically run a 3 to 4 ft long shaft off their diesel engine and have at least 4 pulleys with pillow blocks. They usually run a DC charger for their portable power tools, a compressor for their refrigerators (only allowed if they have a business) and another pulley goes to a compressor to run their tools, which have air motors in them. With that in mind I'm not sure I'll add a pulley at this time, mainly due to money constraints. If I use a Lovejoy coupler it should be a simple matter in the future to just uncouple, add a pulley and be on my way.

I originally thought that the Onan generator was connected to the engine via a stub shaft. I thought all I had to do was disconnect the gen head, slide my ST on with a coupler and I'd be done. I do have a 28mm stub shaft that I'll well on to the little "flex plate" (that gets attached to the flywheel) but I still have to buy a Lovejoy with a 28mm and 42mm ends

The nice thing about this unit is it's kinda like a Joe Home owner model. Everything is nice and compact. All someone (thinking.. the wife) would have to do is turn the swith, plug in the power cord and 240 volsts go to the house.

Randy B

I'll post some pics in a few weeks once I decide what to do and do it. In the meantime I have to finish building the 2 cyl Cat. I hope to break  in the engine this weekend then move it to it's permanent location in the garage.