case half interchangability... ????

[Mattyo]

Yeah I dunno about 15 thou. If I see light on a straightedge. ...it's going on the bridgeport. Often my builds go on the bridgeport anyway. Then the issue becomes... is the mating surface parallel to the crank axis lol. Who knows. Maybe one day I'll get to that level of detail.

I just can't understand how one would manufacture mated case halves. So whether they do or dont...iD love to see a video on how they machine those bearing pockets. That would be proof one direction or another.

 

[dall]

Yeah I dunno about 15 thou. If I see light on a straightedge. ...it's going on the bridgeport. Often my builds go on the bridgeport anyway. Then the issue becomes... is the mating surface parallel to the crank axis lol. Who knows. Maybe one day I'll get to that level of detail.

I just can't understand how one would manufacture mated case halves. So whether they do or dont...iD love to see a video on how they machine those bearing pockets. That would be proof one direction or another.

quit building huskies and the problem is solved

 

[Mattyo]

quit building huskies and the problem is solved

I've decked stihls too

 

[Stump Shot]

Yeah I dunno about 15 thou. If I see light on a straightedge. ...it's going on the bridgeport. Often my builds go on the bridgeport anyway. Then the issue becomes... is the mating surface parallel to the crank axis lol. Who knows. Maybe one day I'll get to that level of detail.

I just can't understand how one would manufacture mated case halves. So whether they do or dont...iD love to see a video on how they machine those bearing pockets. That would be proof one direction or another.

I still say if the dowels line up perfectly, this is all the "proof" you need.
As far as internet folks throwing accusations and making the burden of proof unto you... I'd not worry myself one little bit.
If it's a customer that has some concerns let him/her make the final decision after it's discussed between the two of you.
Otherwise it's a European vacation to Sweden and Germany for factory tours for you.

 

[dall]

I still say if the dowels line up perfectly, this is all the "proof" you need.
As far as internet folks throwing accusations and making the burden of proof unto you... I'd not worry myself one little bit.
If it's a customer that has some concerns let him/her make the final decision after it's discussed between the two of you.
Otherwise it's a European vacation to Sweden and Germany for factory tours for you.

i think you just volunteered to go with him

 

[MG porting]

Stihl sells case halves separately.

. Shhhhhh. Because there better but that's supposed to be a secret.. no I like Husqvarna to but I'll pick a Stihl over one most of the time.

 

[Stump Shot]

I've decked stihls too

You're going to make his coffee salty. Lol

 

[dall]

I've decked stihls too

so you admit its operator error

ive put different cases together and not have a problem

 

[Stump Shot]

i think you just volunteered to go with him

Thanks for buying our tickets. We're going to need Motel stay, ground travel and dinners comped too.

 

[Stump Shot]

so you admit its operator error

ive put different cases together and not have a problem

He does it to set the squish tolerance.

 

[Tor R]

The only thing I would be interested to know is if those two bearing sockets sit flush, and if the base is flush to the bearings.
Easy to figure out though, all that is needed is an axle with a ”spot on” tolerance to the bearings, and then some sizing.

its something I consider to do on all older 550/560 cases, machine the base after the bearings. If I first start to get a friend to mill I can probleby just do the next step also, modd the case for PTO bearing on both sides.
Saw a video from our master monkey, stuff like this is possible.

 

[Mattyo]

so you admit its operator error

ive put different cases together and not have a problem

I'm sure there's some operator error. But some cases line up perfect. Mostly I deck cased to set squish tolerance...but also to get a super smooth and flat surface.

Next time you put two case halves together from different years...hit it with a straightedge and see how ya did.

This is a different issue than whether or not bearing pockets line up / how the factory lines them up.

@Stump Shot is likely right. The only way to know is to get a factory tour
..which is unlikely even if I make it to the factory.

What I love about machine tool is that there always seems to be another approach to a problem. But when I hear things like ...cases are machined while mated together, I start scratching my head.

Carry on gents.

 

[dall]

I'm sure there's some operator error. But some cases line up perfect. Mostly I deck cased to set squish tolerance...but also to get a super smooth and flat surface.

Next time you put two case halves together from different years...hit it with a straightedge and see how ya did.

This is a different issue than whether or not bearing pockets line up / how the factory lines them up.

@Stump Shot is likely right. The only way to know is to get a factory tour
..which is unlikely even if I make it to the factory.

What I love about machine tool is that there always seems to be another approach to a problem. But when I hear things like ...cases are machined while mated together, I start scratching my head.

Carry on gents.

lol i have even when i put a new case half against a old one

 

[MG porting]

lol i have even when i put a new case half against a old one

That must make you the special one.

 

[Bigmac]

I think they machine the bearing pockets, bolts holes and dowel pin locations, then machine the deck as a set. I work more on motorcycles, and the worse case of miss matched cases was on a yfz450, there was a deck difference and they ran it! It ended up destroying in the top end, bending the rod and bending valves. The excessive side loading eventually stuck the piston in the bore, was a mess! Worked on a lot of miss matched Trx250r cases and never had a deck issue, some manufacturers have tighter tolerances, or have been lucky a lot with them! Lol

 

[heavy_oil_saw]

@Mattyo This is is a question I’ve been trying to find an answer to about crank issues. A suggestion was that the case halves were mis-machined at factory, causing excess wear on the clutch end, as it rotated in an oval, or whichever none circular shape it rotated in.
I don’t believe personally two halves of a crankcase could be so badly machines in today’s manufacturing world, especially on high end saws (I’ll await to your replies to this [emoji3]).
Tolerances are in place, in which the crank can happily rotate in, so no problems.
Great to hear you guys have been sticking odd case halves together, with little problem, I’ve got a busted clutch half that needs replacing.
PS I’m not a logger, feller, our builder/modder, just bought a “fried” saw, and decided to rebuild it.


Sent from my iPhone using Tapatalk

 

[srcarr52]

In my experience Husky cases are pretty interchangeable, Stihl's on the other hand usually have inconsistent deck heights.

Bearings bores are not usually a problem as they would be machined in the same fixture as the bolt holes and locating pins, the cylinder deck would have to be done in a different fixture or with a 4th axis to rotate the part.

Machining the bearing bores at the same time really wouldn't be cost effective for most designs. Especially with some Husky designs (394/5) where both bearing pockets have lesser diameter seal bores so you'd have to use a line bore technique with a cuter that is attached on the through shaft through the cylinder flange. Designs like the Stihl 066 where there is no seal lip on the PTO side would be easier to machine all from that side but I still doubt they do it that way, way more accuracy than what is really needed. A standard deep groove ball bearing can withstand some misalignment.

 

[Junk Meister]

Just had a comment on my youtube channel, and its not the first time I've heard, regarding the manufacturing process of case halves for saws. The jist of the comment was that the halves are essentially made specifically for each other and that crank shaft misalignment (bearing pocket bores) is possible when you interchange case halves from different saws within a specific model.

Though I do believe bore misalignment is possible, I don't necessarily believe its because case halves are machined whilst mated to each other. I have a hard time imagining that the case halves are first put together, then the bearing pockets are cut in perfect alignment, then disassembled and reassembled with the bearings and crank.

It makes more sense that individual case halves are made in a jig, possibly using the case bolts /holes and pins as referrence points, and then the bearing pockets are cut ...with reasonably high precision I might add.

If anyone has any actual evidence of how the cases are machined (together, or apart) i'd love to see it or hear it.

I've certainly seen some misalignment over the years, but indirectly. Measuring misaligned bearing pockets would be nearly impossible let alone likely futile. You'd have to install bearings, assembled the case, then put a reference piece of round stock through the bearings? and somehow measure off that? I dunno, seems like the margin for error here would be larger than the misalignment.

The misalignment I have seen somtimes occurs at the part of the crankcase that mates to the cylinder base. one side can be higher than the other. No worries, use the pto side as a reference for flat and use the bridgeport to deck it flat

this vid is relatively short and a bit jittery because I'm holding the camera, but it illustrates one way case halves can be misaligned. ... SLIGHTLY. pto side is a 181 case, flywheel is from a 288 I think.

Long winded so just jump down to the last 2 or 3 lines if ya wanna short cut.

I just read through to post #37 And the OP had the issue of a Keyboard Jockey jabbering at the jowls about case alignment. I gleaned a bunch and gained a bit of comfort learning from everybody... I was welding concrete rebar at the USPS and was critiqued for welding not tying the rebar. Such a trivial statement from the peanut section. My reasoning went from my supervisor to his STUPERVISOR and I was told to carry on. 20 plus feet in th air welding over Very High dollar mail processing equipment / fire watch / Down time for the mail flow and on and on.

Any way scenarios like this are aggravating but I like the logic in post #13 and think my phrase fits - It's like turpentine-corncobs and Cats Arses , if it works just do it So MATTYO ,, what was your response to the UTUBE comment?

 

[Finnrpm]

Stihl sells case halves separately.

Not here in Finland...... asked local dealer because......


RV

 

[Gary Courtney]

The question is why

Did you ever find out why they put the wrist pins in the piston instead of wrapped?