case half interchangability... ????

[Mattyo]

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.

 

[Tor R]

When we're heading back in time, Husqvarna had a far better quality back in the 80's, 90's, 00's compared against what they've been doing last 10 years, I tend to think they've put more effort into the crankcase halfs in those years. I would not take it as granted that they machined the bearing pocket with the same tolerances through the whole 181, 281, 288 era. Most likely they ran batches.

They've never sold crankcase halfs seperatly, not even for the 5xx serie, where the production was quite sloopy until 2017 or so.

 

[Mattyo]

That is interesting @Tor R .... the case halves not being available separately. The question is why.

 

[Mastermind]

Stihl sells case halves separately.

 

[lumberjackchef]

I have seen alot of posts on the interwebs on this subject as well. Despite all the possible problems with the misalignment i have successfully replaced case halves from donor saws on several different ones over the years, 2171, 372, 044,and 066. Never had any issues except for minor differences in the cylinder mating surfaces.

Sent from my moto e5 play using Tapatalk

 

[Tor R]

The one who knows most about Husqvarnas production system is probleby Bob @Spike60, let's see if he can answer some of Matt's question.

 

[Spike60]

This all falls into the fussy yet unimportant detail category IMO.

Ask the guy who made the youtube comment to share his credentials and experience to validate his theory and I'll bet he doesn't have any beyond, I'always thought, I heard, I was told, It just makes sense. In other words, he really doesn't know what he's talking about like 80% of the people on the web. LOL

I don't know why Husky has only sold case halves as a set other than the fact that they are supposed to be a "matched set". How matched they actually are in comparison to two random halves is likely insignificant.

But what I do know from real world experience is that for years, myself and many others have been building saws from the dead saw parts piles and sticking any 2 decent case halves together with no ill affects. I've got some saws where one half the crankcase is red and the other side is orange. Have mixed OE and XT sides of 372's. Often ending up in a commercial use environment.

There may be some issues for cases that were separated over several years like Matt's 181/288 build where there may have been some changes/updates. But for the most part, we don't need to sweat the matched case deal.

 

[Basher]

This all falls into the fussy yet unimportant detail category IMO.

Ask the guy who made the youtube comment to share his credentials and experience to validate his theory and I'll bet he doesn't have any beyond, I'always thought, I heard, I was told, It just makes sense. In other words, he really doesn't know what he's talking about like 80% of the people on the web. LOL

I don't know why Husky has only sold case halves as a set other than the fact that they are supposed to be a "matched set". How matched they actually are in comparison to two random halves is likely insignificant.

But what I do know from real world experience is that for years, myself and many others have been building saws from the dead saw parts piles and sticking any 2 decent case halves together with no ill affects. I've got some saws where one half the crankcase is red and the other side is orange. Have mixed OE and XT sides of 372's. Often ending up in a commercial use environment.

There may be some issues for cases that were separated over several years like Matt's 181/288 build where there may have been some changes/updates. But for the most part, we don't need to sweat the matched case deal.

Don`t let Andy hear you say that, but yeah if one can get the cylinder base to seal on the crankcase the saw will run for years on end, have done so many times but was always reprimanded for doing so.

 

[Stump Shot]

My last attempt to try and use halves from two different saw's failed, as the cylinder deck was at two different height's. This doesn't mean that a different scenario won't work just that things need to be checked out before diving in and building the saw. So if possible I avoid it and if not I double check my triple check, before going forward is all.
Pretty sure one of my saw's was built from two different case halves and I've run it enough to say if there was an alignment problem, it would have manifested itself by now, the deck was even and crank installation went along normally, the dowels came into alignment normally. This wouldn't be the scenario if the bearing pockets were off and about all the "proof" of alignment you need imo.

 

[huskihl]

There is enough slop in the location pins in a Husky to allow for even 2 matched halves to bolt up a few thousandths different in height. I always tighten the 5-7 case bolts, and then loosen them, bolt the cylinder on tight, and then tighten the case bolts. 9 times out of 10 the cylinder mounting area is flush.

 

[Stump Shot]

There is enough slop in the location pins in a Husky to allow for even 2 matched halves to bolt up a few thousandths different in height. I always tighten the 5-7 case bolts, and then loosen them, bolt the cylinder on tight, and then tighten the case bolts. 9 times out of 10 the cylinder mounting area is flush.

This is a good tip and it saved me a few times.
The case however that I mentioned was way off like over .020" off, if memory serves. There was no making it even without breaking out a wood router and a belt sander. Lol

 

[huskihl]

This is a good tip and it saved me a few times.
The case however that I mentioned was way off like over .020" off, if memory serves. There was no making it even without breaking out a wood router and a belt sander. Lol

Hey man, quit letting all the secrets out

 

[Mastermind]

I put an 034 case half together with an 036 half. There were a great many years difference, and the deck heights were off about .020". Not a problem. Glued a half a gasket down on one side, and carried on. Ended up giving the saw to a friend, and he still has it.

 

[Mastermind]

Point is, we ain't building space shuttle engines.....sometimes a little common sense is all you need to make an old saw cut wood again.

 

[huskihl]

I put an 034 case half together with an 036 half. There were a great many years difference, and the deck heights were off about .020". Not a problem. Glued a half a gasket down on one side, and carried on. Ended up giving the saw to a friend, and he still has it.

Lol. Awesome

 

[jacob j.]

I put an 034 case half together with an 036 half. There were a great many years difference, and the deck heights were off about .020". Not a problem. Glued a half a gasket down on one side, and carried on. Ended up giving the saw to a friend, and he still has it.

Lol. Awesome

I built an 066 for a timber faller buddy that was the same way - he got three years out of it as a back-up saw before the crank went. He was running a 36" bar on it.

 

[Stump Shot]

I put an 034 case half together with an 036 half. There were a great many years difference, and the deck heights were off about .020". Not a problem. Glued a half a gasket down on one side, and carried on. Ended up giving the saw to a friend, and he still has it.

Pffft, you could have eyeballed .020" off of half the cylinder with a big belt sander. Lol

For bonus points you could have saved the shavings and dumped them in.

Seriously though, in Matty's case if he's going to set it up in a milling machine anyways...

 

[Stump Shot]

Hey man, quit letting all the secrets out

Once you see them swirls, it's hard to forget.

 

[Red97]

Pffft, you could have eyeballed .020" off of half the cylinder with a big belt sander. Lol

For bonus points you could have saved the shavings and dumped them in.

Seriously though, in Matty's case if he's going to set it up in a milling machine anyways...

If we only talking. 020, use some 518 and a tin can gasket...

518 claims good for a .015 gap...

 

[Stump Shot]

If we only talking. 020, use some 518 and a tin can gasket...

518 claims good for a .015 gap...

My crazy mind was already spun out on wwjmsd. Lol
Sometimes I start at what not to do and go from there.
Probably lots of different fixes for this in reality.
Again, in the op's case, he's decking the crankcase already, so it's a non issue.