case half interchangability... ????

[Lightning Performance]

Matty... your way too anal for a guy with a mill.
You better buy some more tools to figure out if your balls are in alignment :Facepalm:

I'll mail you a two piece base gasket set of different thickness.

Go read Randys post again and bury this thread.

 

[Mattyo]

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

nope, husky hasn't gotten back to me yet. i doubt they will at this point.

 

[Mattyo]

Matty... your way too anal for a guy with a mill.
You better buy some more tools to figure out if your balls are in alignment :Facepalm:

I'll mail you a two piece base gasket set of different thickness.

Go read Randys post again and bury this thread.

If its uniformly off, by a fixed amount, then randy's fix would work. but what if its not? if its 15 thou high in the front, then 15 low in the back, how are you going to fix that without decking it? I don't think thats being anal, just being reasonable about getting a head to fit on a set of cases.

but thats not the point. The real question is in regards to the fact that deck heights can be off, therefore bearings pockets are too, therefore cases are machined as a mated set. which just seems like jumping to a pile of conclusions to me.

@srcarr52 has a good summary. likely bearing pockets are machined in a jig with reference to the case bolt holes and the mated case half surface. @Bigmac also said those case halves might be assembled and then decked. but still, its all in reference to those case bolt holes. so they can't be that far off, and often they are dead on, even over multiple years, and multiple brands.

here's the video that was commented on @Junk Meister

Bill commented that the cases were machined assembled and that by using different case halves the bores can be misaligned. I asked how they were machined assembled?

sorry gents, its an old vid at this point.

as i've often stated, sometimes I'm on my phone and don't get to post as thorough of a question or answer as I'd like, so sorry if answers are too.. uh.. short

 

[angelo c]

If its uniformly off, by a fixed amount, then randy's fix would work. but what if its not? if its 15 thou high in the front, then 15 low in the back, how are you going to fix that without decking it? I don't think thats being anal, just being reasonable about getting a head to fit on a set of cases.

but thats not the point. The real question is in regards to the fact that deck heights can be off, therefore bearings pockets are too, therefore cases are machined as a mated set. which just seems like jumping to a pile of conclusions to me.

@srcarr52 has a good summary. likely bearing pockets are machined in a jig with reference to the case bolt holes and the mated case half surface. @Bigmac also said those case halves might be assembled and then decked. but still, its all in reference to those case bolt holes. so they can't be that far off, and often they are dead on, even over multiple years, and multiple brands.

here's the video that was commented on @Junk Meister

Bill commented that the cases were machined assembled and that by using different case halves the bores can be misaligned. I asked how they were machined assembled?

sorry gents, its an old vid at this point.



as i've often stated, sometimes I'm on my phone and don't get to post as thorough of a question or answer as I'd like, so sorry if answers are too.. uh.. short

if its .015 shorter in the "front" and .015 longer in the "back" is it still a "Mullet" or a "Mall-ette" ...

 

[jmester]

I also have used mismatched case halves. And as most have said the biggest problem I have had and seen is the deck height being off one side higher then the other. I find it interesting that stihl would only sell both case halves for older saws and now sell fly or PTO sides separately.

 

[Bigmac]

I also have used mismatched case halves. And as most have said the biggest problem I have had and seen is the deck height being off one side higher then the other. I find it interesting that stihl would only sell both case halves for older saws and now sell fly or PTO sides separately.

I bet they cnc machine each side now completely, the older way of matching probably isn’t needed with better tooling. I bet that the used to machine the deck as a matched set, but if the accuracy is there in the machine work then matched sets wouldn’t be an issue, it would also explain the wide variations is squish in the older Stihl’s

 

[drf256]

May have to lay off the Mexican food Doc...

 

[Deets066]

Brrrraaapp.....

 

[Deets066]

How do you get zero runout from just clamping in the vice Matty?

 

[Mattyo]

It takes a while to get it clamped so there the table travel is parallel to the existing deck. Tap and clamp and tap and clamp. Also....I'm only cutting magnesium...and most of the time only removing 20 thou. Much different than cutting steel. If i clamp the mag case too tight i can break it. Havent broken one yet. Probably done around 50 decks at this point.

 

[Deets066]

Tapping it in the vise only helps in one axis. The other axis won’t change unless shimmed in the vise.

 

[Mattyo]

Sorry..it gets shimmed with wood blocks to adjust the flywheel /pto axis... and it rocks from to back naturally anyway. I think front to back is the axis you were referring to.

 

[KennyWinCT]

Bill commented that the cases were machined assembled and that by using different case halves the bores can be misaligned.

I asked how they were machined assembled?

You can Back-Bore an assembled case. The tool bit swings out when you rotate the spindle in one direction and returns to it's home resting place in the tool's body when rotated in the other direction to allow the tool to go in and out of the hole(s).

I would think that with CNC technology, and having designed and built machine tools since the 90's that holding half a thou true position on a bearing bore using the locating pin holes or whatever datums are machined in the case half would not be too difficult. In that vein, I would say that machining them separately is a totally feasible task by any competent machining supplier. That being said, ideally you would get the best result (Co-linearity) if the case was assembled then machined. This harkens back to when Cadillac started using Johansson Blocks and made interchangeable parts

 

[Mattyo]

Ah... so you have a bit that expands when rotated one direction yet collapses going another.... hmm.

Vids? Any example I can see?

 

[KennyWinCT]

Ah... so you have a bit that expands when rotated one direction yet collapses going another.... hmm.

Vids? Any example I can see?

Used primarily for back spot facing but I've used similar tools for back boring.

 

[Mattyo]

Pretty slick tool if ya ask me. Very interesting!

 

[legdelimber]

Mind you that my shop time was all spent around manual machines.
Plus it's been a good while since then.
But my reflex at the proportions of the flapper tool had me concerned with it wanting to squeal & chatter in that back facing mode.
The vid made think of something with a .750" to 1.25" shank and the cutting wing cutting face length being close to the diameter of the tool shank.
Is there more to it than that conceptual animation?
Perhaps cutting angle is trailing the shank (on a tangient?) vs being strait out the shank?
I know cutter edge angles and heel relief can play a lot in things.

Please forgive my horribly atrophied usage of vernacular, it's been waayy too long since I grabbed the handle and levers.
shoot, I wonder if I still even would have the coordination to (gracefully) crank the handles and run that loop on the deck of the cases anymore?

Once upon a time I was able to dress a bench grinder wheel (fine grit) to an angle and then hand grind my drill bits.
Could get the end angles and sweep the bit to get heel clearance, then split point grind to thin the center web for reduced feed pressure.
Eyesight is long gone for doing that trick any more.

 

[KennyWinCT]

"Is there more to it than that conceptual animation?
Perhaps cutting angle is trailing the shank (on a tangient?) vs being strait out the shank?
I know cutter edge angles and heel relief can play a lot in things."

The cutter shown in the animation is a back spot-face tool, where tolerances on OD dimensions are not that critical (+/-.005"). We used to make our own back-boring tools with the correct geometry to remove minimal material from die-cast housings that left .030-.040 stock per side for final machining. we held +/- .0005" on the bore diameter. Also, we are talking magnesium or aluminum case material, NOT steel or cast iron so that the demands on the insert are not as tough.

 

[legdelimber]

Yeah, I was thinking that if the back facing was for softer metals, that chatter would be much less likely to happen. I expect the tool being under tension also helps a little. Interesting the things that help keep cutting tools from resonating.
If you get a chance to look at a NewWay brand valve seat cutter head, you can see that the (3) inserts have a varied spacing.
Ah, but figuring out solutions was just part of what made the job "interesting". Some days at least.....

 

[KennyWinCT]

If you get a chance to look at a NewWay brand valve seat cutter head, you can see that the (3) inserts have a varied spacing.

I LOVE my Neway Seat Cutters. Been using them for years. The factory ground some custom guide pins for me so they wouldn't be so tight or sloppy in the guides I was using. Price was not bad either. Nice people.