Husqvarna 390xp build

[farminkarman]

A while back I picked up this NIB 390xp from a member here on OPE forum. It finally made the top of my list for shop projects, so I thought I would try to document as much of the process as I can. This is my first time cracking open a 390xp, so I am definitely not an expert. At the end of this, I am hoping I have a reasonable recipe to work off of for future builds, and be able to have a nice logging saw to put up for sale. Here are the pics of the saw as I bought it:

 

[farminkarman]

I started by removing the top plastics, recoil assembly, top handle, and the muffler. Then I pulled the cylinder & intake assembly off the saw. After removing the intake, spark plug, and decomp from the cylinder, I mounted the cylinder to a plate that I can mount on my 4-jaw lathe chuck.

 

[farminkarman]

After getting the cylinder indicated to less than .001” runout from the top to the bottom of the cylinder, I cut the squish band. For this build, I decided to take 0.040” from the band. While the cylinder is chucked in the lathe, it is a great time to also cut the cylinder extensions.

 

[farminkarman]

I will keep posting pics and info to this thread as I progress through the build.

 

[srcarr52]

After getting the cylinder indicated to less than .001” runout from the top to the bottom of the cylinder, I cut the squish band. For this build, I decided to take 0.040” from the band. While the cylinder is chucked in the lathe, it is a great time to also cut the cylinder extensions. View attachment 350399View attachment 350400

It's also a good time to turn your compound and put a new chamfer at the bottom of the bore to help push the rings in during install.

 

[farminkarman]

It's also a good time to turn your compound and put a new chamfer at the bottom of the bore to help push the rings in during install.

Good call on that Shaun. I have been using my grinder to do the bevel, but doing it on the lathe makes more sense!

 

[farminkarman]

Before I cut the base, I like to do any lower transfer work. On this one, I cut the edge of the cylinder extension back toward the exhaust to unshroud the entry to the primary transfers.

 

[Kiwioilboiler]

@Woodrow

Oh, sorry. Force of habit when I see NIB....

 

[jacob j.]

I think this would get more hits if it were in the chainsaw section @Woodpecker

 

[farminkarman]

@Woodrow

Oh, sorry. Force of habit when I see NIB....

Methinks @Woodrow would have already bought it if it were the red & black variety.

 

[Woodpecker]

I think this would get more hits if it were in the chainsaw section @Woodpecker

Thanks JJ I don’t care what Greg says about you you’re alright… FFS Greg! You’re fired you can’t do anything right

 

[farminkarman]

Thanks JJ I don’t care what Greg says about you you’re alright… FFS Greg! You’re fired you can’t do anything right

I never was good at being right, lol.

 

[farminkarman]

Managed to get out to the shop before work again this morning. Finished up the lower transfers and then cut the base.


.

 

[Mastermind]

Chainsaws!!!!! YUCK

 

[farminkarman]

Chainsaws!!!!! YUCK

I hate em so much that I can’t even count how many are in the shop right now.

 

[srcarr52]

Managed to get out to the shop before work again this morning. Finished up the lower transfers and then cut the base.

View attachment 350564
.View attachment 350561View attachment 350562View attachment 350563

That insert is for cutting steel. Switch to a CCGT insert and you'll get a better finish.

 

[farminkarman]

That insert is for cutting steel. Switch to a CCGT insert and you'll get a better finish.

When I bought this tool, it came with a couple of these CCMT inserts. I did purchase a package of the CCGT inserts, but these ones have been laying down a really nice finish, so I have been using them. Perhaps I will switch and save these inserts. You should be charging for all the machining advice

 

[redline4]

For those unedumacated non machinist people like myself, what is CCMT and CCGT?

 

[farminkarman]

For those unedumacated non machinist people like myself, what is CCMT and CCGT?

I will be honest that I am not positive what all the letters mean…Shaun could probably set the record straight. Iirc, “M” refers to general tolerance class, and “G” refers to ground finish. The smoother finish is supposed to work better for cutting aluminum.

 

[srcarr52]

For those unedumacated non machinist people like myself, what is CCMT and CCGT?

The first letter is the shape (C=diamond), second is the relief angle (C=7deg).

Now the fun begins.
The third letter is tolerance, M being generally molded, G being ground (Sharper but more fragile).

Forth is the hole type, T=countersunk.