Homelite, Poulan, McCulloch etc. Press Fit Wrist Bearing Pulling Made Simple Solution

[Duke Thieroff]

This is a common style rig found in a lot of older American saws and a major drawback when it comes to rebuilding them because of the added complication of taking them apart.

A few examples:
Homelite 330
Homelite 350, 360, 450, 550, 650, 750
Poulan 3400,3700,3800,4000 etc
Mac 10-series
Mac 600 Series
Mac Large Frame

I started doing so research and found that there really is no reliable source of new or home-brew tools and I am a major fan of making simple off the shelf solutions that work. We have some things in the works that are going to require some tool solutions for guys so I set out to work on figuring out this little problem.

After a little research I came across a tool called called simply "Wrist Pin Extractor Removal Tool." They're all over internet through all major reseller marketplaces for $10-20. It seems no matter the brand they're all the same design. The unfortunate things is that they are mainly designed with the ATV/Motorcycle market in mind and come with an M8-1.25x70mm Socket Cap Screw as the extractor. They M8 head measures 12mm which is generally too large for all applications in chainsaws.




It was a little bit of a letdown when I got it in and found it wouldn't work for what I needed it to so I got to brainstorming the solution and after some research I determined that I could probably get by with an E-Z Lock thread insert (M5-0.8ID x M8-1.25OD) and an M5-0.8x70mm socket cap screw. You'll have to do some measurements yourself and decide on whether or not you want to step down to an M5 or M6 for your particular application. I'm sure you could run them both into the barrel with the M5 in first to have a truly modular setup.

For this demonstration I'm going to use a junked Mac 10 or 6xx something. Had to do a little bit of shimming (just a folded up kraft paper box) because of the design of the piston. I ran with the M5 screw here. It seems these are big enough you could get away with an M6 with proper insert if you wanted to. You may even want to line the tool side with something a little softer as well because the tool is made out of steel and could potentially damage your piston. There's a TON of different ways you could go with that.



Gotta fool around a bit just to make sure you're lined up and start cranking her down.

 

[Duke Thieroff]

Here's a look at some beginning progress. You'll probably want to have a new set of bearings in hand for these. (I know most of the sizes if you need to know.) The rollers have a tendency to pop out when you take them apart. Most of them have the number stamped into the side usually B-6x or B-7x. They're all still common to find but you may have to go with KOYO or different brand than Torrington.


Here's an "action shot." A ton of science is taking place in front of your eyes....mainly me being able to get this done without burning the shop down.



Oh baby, here we go AND we don't have to worry about bending the connecting rod!


And there is is, painlessly removed in a matter of minutes.





Perfect.

If you want to make one just like this you will need:

-Wrist Pin Extractor Tool
-E-Z Lock #453-5, Thread Insert M5-0.8x M8-1.25
-M5-0.8x70mm Socket Cap Screw

Thanks guys!
Duke

 

[Dub11]

I dig it! Thanks.

 

[Al Smith]

Thanks for the idea

 

[Duke Thieroff]

I dig it! Thanks.

Sure thing bud!

Thanks for the idea

I tried with this and a Poulan 3400 piston. It works perfectly. Worth $20

 

[Czed]

My way is not so elegant.
Lot's of hammering.

 

[Duke Thieroff]

My way is not so elegant.
Lot's of hammering.

Bull in a China shop, eh?

 

[Mastermind]

Good stuff Dooky.

 

[Duke Thieroff]

Good stuff Dooky.

Thanks Hoss.

I'm a little bit tickled over it myself.

 

[Al Smith]

FWIW if you wanted to the head on a grade 8 socket head cap screw is soft enough it can be cut down with a lathe .--- just a thought ---

 

[Duke Thieroff]

FWIW if you wanted to the head on a grade 8 socket head cap screw is soft enough it can be cut down with a lathe .--- just a thought ---

Hey Al!
Thanks for the response!

I don't know nothing about machining parts but I'm positive you're correct.

The problem is not only the diameter of the head but also the diameter of the bolt itself. If I remember correctly the Poulan wrist pin only measures about 6mm ID. The M5 is the only rig small enough to make it work.

I'm pretty sure with an M5 and and M6 you would be covered on just about all of these type setups in the chainsaw world.

 

[Al Smith]

Well I'm going to delve into it .I've never removed a pressed in pin and have always just changed the piston/ rod assembly as a unit .
However as my things to do list is growing daily I do have a 700 Mac and an 805 with gnarly pistons but with cylinders that should clean up .When that happens I have not a clue at the moment .Got a lot of irons in the fire so to speak .

 

[Duke Thieroff]

Well I'm going to delve into it .I've never removed a pressed in pin and have always just changed the piston/ rod assembly as a unit .
However as my things to do list is growing daily I do have a 700 Mac and an 805 with gnarly pistons but with cylinders that should clean up .When that happens I have not a clue at the moment .Got a lot of irons in the fire so to speak .

I know that feeling. Not a bad thing to change the whole works as an assembly.

Sometimes it's not the most practical. I remember having to replace all the loose needles on a Mac 1-76 one time. They don't have a split crankcase so you have to install them with the piston and rod in the bore. A lot of counting and re-counting went into that job.


If you ever need a toll I'd be willing to let you borrow this one!

 

[Al Smith]

Appreciate the offer .Actually in my rather redneck engineering mind I had thought about using a Greenlee knock out punch with a modified pull bolt .
I don't want to skew the thread but before you could buy the Stihl flywheel pullers for a reasonable price being a tightwad I made them from a metric hydraulic
"banjo " fittings using an 11 MM Ford cylinder head bolt .
To me it's a challenge to out fox the fox in a manner of speaking .Especially with German engineering methods where they try to establish they can control replacement parts and repairs with the requirement of special tools .Might work with some people not me ."yankee " ingenuity ! On that ,there's always several methods to skin the same cat. Nice to see other methods .

 

[Duke Thieroff]

Appreciate the offer .Actually in my rather redneck engineering mind I had thought about using a Greenlee knock out punch with a modified pull bolt .
I don't want to skew the thread but before you could buy the Stihl flywheel pullers for a reasonable price being a tightwad I made them from a metric hydraulic
"banjo " fittings using an 11 MM Ford cylinder head bolt .
To me it's a challenge to out fox the fox in a manner of speaking .Especially with German engineering methods where they try to establish they can control replacement parts and repairs with the requirement of special tools .Might work with some people not me ."yankee " ingenuity ! On that ,there's always several methods to skin the same cat. Nice to see other methods .

I like it.

 

[Stump Shot]

Thanks Hoss.

I'm a little bit tickled over it myself.

Good job Duke!
Question now is... what's the chances of a ready made unit for sale in a certain entrepreneurs online chainsaw supply store???

 

[Duke Thieroff]

Good job Duke!
Question now is... what's the chances of a ready made unit for sale in a certain entrepreneurs online chainsaw supply store???

I'd say probability is rather high in the next couple weeks



I figured I'd share all of the information here for the tinkering sort.

 

[Stump Shot]

I'd say probability is rather high in the next couple weeks



I figured I'd share all of the information here for the tinkering sort.

Let us know when that happens.

 

[Duke Thieroff]

Let us know when that happens.

 

[Stump Shot]

Nice! I think I will be getting one for my PM700 project. I would otherwise use my arbor press and it's not easy to do with only two hands to do the doing. Not that an arbor press isn't handy for a saw shop, it really can do 1001 jobs for a fella, but when something else is easier and slick like this, well...