Plastic saws?

[dynodave]

What is the type of plastic used for, such as , poulan 2150s or my husky 41. The exact type of plastic would be useful. I want to do a seam fix. I have all kinds of solvent based glues, epoxies and heat welding. Also what is the manufacturing process for original factory joints?

 

[s sidewall]

The cases are Sonic welded, not glued.

Steve

 

[s sidewall]

Saw it on how it's made.

Steve

 

[alexcagle]

I saw a machine sonic welding plastic tanks together at the US Stihl plant a couple years back. Very unusual.
If you get too close to an automated machine, or an automated forklift, it will stop for a bit.
The piston machining robots in an enclosure were cool.
The plastic injection moulding media pellets are run through a vast network of conduits.
The 1.2million sq foot plant tour was something I'll never forget. Very Cool.

 

[Conquistador3]

Most plastic parts have information material stamped on them.

For example my MS231 and MS193T have their plastic parts stamped "PA66 GF30" which means they are made from polyamide 66 (a non-trademark name for Nylon 6,6) reinforced with 30% glass fiber. Many motorcycles from 2000-2005 have their plastic fairing parts stamped "ABS GF30", meaning acrylonitrile butadiene styrene (ABS thermoplastic, the stuff LEGO bricks are made of) reinforced with 30% glass fiber.

You understand the standard format for PMC's (Plymer Matrix Composites) is to give first the main component (PA66) and then the reinforcement (GF30). While glass fiber is by far the most common reinforcement, a glassfiber mat ( #%gl.mat) is used in several applications and carbon fiber (#C) is becoming more and more widespread.

Hope this helped you out.

 

[dynodave]

Thanks all. I want to repair the front oil tanks seam that may have been cracked during some PO accident prior to it being scrapped in the transfer station at my BIL's town. The saw seems OK other than a sloppy oil leakage/consumption issue.
The oil consumption was reduced when the bar was changed from a small husky D095 bar to the correct D041. The bar oiler hole over shot the saw oiler channel by .100" . Next the oil tank stopper had both oil orings undersize and became oil tight with the correct orings, But finally with the saw standing up on the bar, after not to long a period, the seam still oozed bar oil.
It may come down to a small ball shaped dremel carbide bit to partially excavate the seam and solvent or epoxy glue it sealed. The saw is complete, runs well for what it is, but not worth a lot of money. So this level of repair is all I want to invest.
pix of the saw is in my gallery
I'm seeing PA6-GF33

 

[Conquistador3]

Thanks all. I want to repair the front oil tanks seam that may have been cracked during some PO accident prior to it being scrapped in the transfer station at my BIL's town. The saw seems OK other than a sloppy oil leakage/consumption issue.
The oil consumption was reduced when the bar was changed from a small husky D095 bar to the correct D041. The bar oiler hole over shot the saw oiler channel by .100" . Next the oil tank stopper had both oil orings undersize and became oil tight with the correct orings, But finally with the saw standing up on the bar, after not to long a period, the seam still oozed bar oil.
It may come down to a small ball shaped dremel carbide bit to partially excavate the seam and solvent or epoxy glue it sealed. The saw is complete, runs well for what it is, but not worth a lot of money. So this level of repair is all I want to invest.
pix of the saw is in my gallery

If the part is Nylan/polyamide like I suspect, you should consider reinforcing it with fiberglass before using an epoxy resin. It will look terrible but will hold (unless the damage is really bad) and be structural sound: some people occasionally report success with hot glue, but it's more or less like rolling a dice.
As far as I know there are no easily available glues that will hold Nylon/PA, or at least not well enough to make a good seal like you need. Preparing the part with coarse sandpaper is the best/cheapest way to give the resin something to hold on to.

But, again, check the saw for markings to find out what the shell is made of. I lean towards reinforced PA6 (Nylon 6), perhaps PA66 but not even I go around dismantling saws just to check what material they are made of.

 

[grizz55chev]

Thanks all. I want to repair the front oil tanks seam that may have been cracked during some PO accident prior to it being scrapped in the transfer station at my BIL's town. The saw seems OK other than a sloppy oil leakage/consumption issue.
The oil consumption was reduced when the bar was changed from a small husky D095 bar to the correct D041. The bar oiler hole over shot the saw oiler channel by .100" . Next the oil tank stopper had both oil orings undersize and became oil tight with the correct orings, But finally with the saw standing up on the bar, after not to long a period, the seam still oozed bar oil.
It may come down to a small ball shaped dremel carbide bit to partially excavate the seam and solvent or epoxy glue it sealed. The saw is complete, runs well for what it is, but not worth a lot of money. So this level of repair is all I want to invest.
pix of the saw is in my gallery

JB Weld it!

 

[scottr]

Dynodave, did the oil tank vent survive the accident on your 41 ?

 

[dynodave]

Dynodave, did the oil tank vent survive the accident on your 41 ?

Yes the little sintered bronze filter is in place. I drained the bar oil out and filled the tank with cleaning tank kerosene. Trying to air blow off the surfaces to dry it off, I get an endless paint spray gun type discharge above the gas tank handle body. The breach is probably above the holding bar. Maybe the screws are too long and vibrated a hole in the tank. I'll find out soon enough.
I had cut open a junk poulan pro 221 oil tank once to see how they were made.
I also had repaired a cracked chain catch socket on a craftsaman (poulan 2150 type saw), holds the oil just fine now, but no chain catch anymore.

 

[scottr]

Looking through the oil tank fill I can see the bill of the duckbill valve . Did yours survive the accident ?

 

[Dave Mccarthy]

Know any aircraft mechanics? Get a semkit of 1422b1/2 clean it up good with solvent. Rough it up with 200 grit and tape the area off. Next smear the sealant on there. It looks like peanut butter and will look horrible, but it will never leak again.plus you can paint it after.

 

[HarleyT]

The cases are Sonic welded, not glued.

Steve

I didn't know that these guys could weld too!!!!

 

[dynodave]

No duck bill. In my oil tank there is only the sintered bronze vent/plug, it looks the same from both sides. It is on the bar mounting pad just below the very front of the oiler canal.
leak...Found -it
Pulled the handle/gas tank off and can now see the bottom seam of the oil tank. No visible crack, but the seam blows kerosene out like crazy with the blow gun nozzle aimed across the seam.

 

[grizz55chev]

No duck bill. In my oil tank there is only the sintered bronze vent/plug, it looks the same from both sides. It is on the bar mounting pad just below the very front of the oiler canal.
leak...Found -it
Pulled the handle/gas tank off and can now see the bottom seam of the oil tank. No visible crack, but the seam blows kerosene out like crazy with the blow gun nozzle aimed across the seam.

See post #8

 

[dynodave]

See post #8

JB Weld it!

JB weld is a company, not a specific product?

1. What is the type of plastic used for, such as , poulan 2150s or my husky 41.
I'm seeing PA6-GF33
2. what is the manufacturing process for original factory joints?
ultrasonic weld
3. I have all kinds of solvent based glues, epoxies and heat welding.

Thanks anyway...I already possess 5 different epoxies and will select the most suitable based on the helpful reply's received
Cheapest new tank/chassis is $35 at sears... typical husky outlets is $48-$60+
This whole exercise is not financially motivated just to fix a $50(max) saw
If successful, my fix will be under $2 plus time and what I have learned will be well worth it for future reference.
Will post pix and description of repair process when completed.

 

[Conquistador3]

JB Weld it!

JB weld is a company, not a specific product?

1. What is the type of plastic used for, such as , poulan 2150s or my husky 41.
I'm seeing PA6-GF33

Polyamide 6 (Nylon 6) reinforced with 33% glass fiber. It's still commonly used in automotive, especially by US manufacturers such as Ford but has been largely superseded by PA66 GF30 in other applications.

JB Weld is a popular two-part epoxy adhesive: https://www.jbweld.com/collections/epoxy-adhesives/products/plasticweld-syringe Available in other formats as well.
As an epoxy it should do the trick on PA, just to be sure sand the area to be treated with coarse sandpaper to give the epoxy something extra to hold on to.

 

[TimberWolf530]

I bought a plastic welder from Urethane Supply Company, who has since changed their name to Polyvance. With my welding kit came a book called "The Book of Plastic Repair" it has a chart to help you identify the type of plastic as well as excellent instructions on how to repair different plastics. I have attached it here for you.

 

[dynodave]

Some pix of the repair process of the defective ultrasonic welding.
The tank was kerosene washed, isopropol washed, and then industrial strength degreaser washed.
The epoxy was applied around 3/4 of the whole seam.
The hole above and to the front of the bar stud is the sintered brass tank vent.
The 2 black sharpie lines border each side of the epoxy
[photo=medium]4967[/photo]
seam behind flywheel
[photo=medium]4968[/photo]
There was definite holes in this bottom seam with sunlight easily visible when looking in the oil fill hole.
The old defective welded plastic was easily picked away with a dental pick, A slight vacuum was applied to suck some epoxy into the seam.
On the bottom it was walnut shell blasted 3/4" wide stripe for better adhesion.
[photo=medium]4969[/photo]
The tank end cap subassembly, on the right, is slid down compared to main body. Maybe only 20 % overlap on the top and bottom seams where ultrasonic welded. The vertical seams should have been OK.
[photo=medium]4970[/photo]
Looking in the fill hole, you could see several slits of clear sunlight holes at the bottom seam. Light green marker is general outline of entire ultrasonic weld joint.
[photo=medium]4971[/photo]
Now to assemble the saw and give it a try.

 

[s sidewall]

Pictures didn't post

Steve