I've been busy designing & 3d printing stuff...

[Chris-PA]

So tonight I drew up a Zenoah GZ4000 oil pump worm drive gear:



Tomorrow I'll try to print it if I have time.

Also, I'm trying to figure out how to insert a zipped up version of the .STL output file needed to print it. I can upload it but now what? Oh, I see it is below.

So that means we can share files for printing parts on the forum, which is pretty cool.

 

[chadihman]

Crazy cool!

 

[BBP]

They are highly valuable for reverse engineering molded parts that have complex geometry like pump casing, impellers things of that nature. Then those files can be used in a 3D printer to build sand molds for casting all different metals.

When can I expect my 100cc, ported, 461 cyl molds to be ready?

 

[Chris-PA]

This oil pump worm is pushing the limits of what can be printed. The first attempt was hopeless, but we were experimenting with higher temperatures to get get better fusing/adherence of the strings. Unfortunately the support structure it put in was really fused too, and difficult to get off, and the higher temperatures caused some loss of shape/definition. I tried a second one with different material and different settings, and it might be pretty close.

Ultimately, if this is actually printable I'll probably want to get a roll of nylon material for it.

Like I've said, this process has a LOT of limitations.

 

[Chris-PA]

When can I expect my 100cc, ported, 461 cyl molds to be ready?

Meh, I'm going to do a 60cc Wild Thing jug first. I love sleepers.

 

[Chris-PA]

Here is a shot showing how the slicer builds up a support structure to hold up overhanging portions of the part - it was oriented so that this face was down. The discoloration was because I switched from black to orange plastic and there was some black material still in the extruder head (sorry - was having focus issues again).
That stuff is actually quite a PITA to cut out of there. Here are the threads - they are not all that well defined, but they seem to engage and turn the oil pump OK:

I rand a drill bit down the center so it would fit the crankshaft properly. This is it assembled on a scrap engine case with the oil pump bolted on:

The drive sprocket fits in snug:


So I designed that one because I had the pump but no worm gear. However there are two designs for these pumps, one using a 19mm worm shown here (from a Craftsman-branded GZ4000), and another using a 21mm worm that is used on the the GZ400/Ryobi 10532, the Jenn Feng clones and the Earthquake 38cc & 41cc engines. The 21mm is what's in all my saws and I don't feel like removing the pump, so this part is not really useful to me and I designed a 21mm part and will print that Monday. Here is the printed 19mm and a real 21mm:


Once I make that I will put it in a saw and see how many crankshaft revolutions it lasts - I'm thinking maybe it will last a dozen. Seriously though, this is a tough application as the chain can rub against it and chips and noodles get packed in there. After all, the factory parts fail and they appear to be molded nylon. This kind of mechanical part that spins at 10,000rpm is probably beyond what is appropriate for this technology - but it will be interesting to see.

 

[LegDeLimber]

What are the chances that if you incorporated a lead out groove into the gear?
Start the notch at about where the spiral/threads run to the face of the flange(?)
and then the groove spirals outward to the outer edge of the flange.
Perhaps this could allow a little bit of self clearing threads??

I grabbed your pics and defaced 'em little in effort to hopefully convey my wonderings.
The face view shows roughly how I would place and curve out the groove.
It would need to be in whatever proper orientation needed so as to outfeed the grime.
This also needs the worm threads to be feeding the gunk towards the face and into the cleanout spiral.
I do realize that the plunger gear will likely only run in an area
that is similar to the black dot I put on the side view of your other pic.
So might not provide the ideal transfer of said grime.

been a long couple days, so I may just be crazy here.

oh yeah, maybe if you run the threads a slight bit "thick"
then a few mins with a small triangle file would dress them into shape
and a nice slick fit.

 

[avason]

How long does it take to make one of those not counting the time on the CAD program? Just curious

 

[Chris-PA]

What are the chances that if you incorporated a lead out groove into the gear?
Start the notch at about where the spiral/threads run to the face of the flange(?)
and then the groove spirals outward to the outer edge of the flange.
Perhaps this could allow a little bit of self clearing threads??

I grabbed your pics and defaced 'em little in effort to hopefully convey my wonderings.
The face view shows roughly how I would place and curve out the groove.
It would need to be in whatever proper orientation needed so as to outfeed the grime.
This also needs the worm threads to be feeding the gunk towards the face and into the cleanout spiral.
I do realize that the plunger gear will likely only run in an area
that is similar to the black dot I put on the side view of your other pic.
So might not provide the ideal transfer of said grime.

been a long couple days, so I may just be crazy here.

oh yeah, maybe if you run the threads a slight bit "thick"
then a few mins with a small triangle file would dress them into shape
and a nice slick fit.

Well, at this point I was just trying to duplicate the original as closely as possible. And in truth I'm just learning to use the CAD package. It took me quite a while to figure out how to draw those threads to a custom spec. There is a lot more I could do and will learn as time goes on.

How long does it take to make one of those not counting the time on the CAD program? Just curious

This part took about an hour.

 

[one.man.band]

chris....... general question here.

can the 3D printer output size ratio of the part be modified? or are you stuck with just 1:1 ratio with original part?

thanks
-omb

 

[Chris-PA]

chris....... general question here.

can the 3D printer output size ratio of the part be modified? or are you stuck with just 1:1 ratio with original part?

thanks
-omb

You can scale the part in a number of ways. You can change how you draw it in the original CAD package, and you can scale it on import to the "slicer" package. I need to do some calibration of the prints ours does, but have not felt like spending the time or material. So far it appears the scaling error is small enough not to matter on parts of this size.

 

[one.man.band]

You can scale the part in a number of ways. You can change how you draw it in the original CAD package, and you can scale it on import to the "slicer" package. I need to do some calibration of the prints ours does, but have not felt like spending the time or material. So far it appears the scaling error is small enough not to matter on parts of this size.

then do some calibrating to scale it into a high output oiler!

 

[Chris-PA]

then do some calibrating to scale it into a high output oiler!

I could simply redefine the thread characteristics in the worm to a "steeper" pitch - but I have found these saws to oil just fine. However, that would put more side force on the threads of the worm gear, and I'm skeptical this part will hold up as it is.

 

[LegDeLimber]

I like the idea of improving output, but I believe the plunger threads would need changing to match.

 

[Marshy]

You can scale the part in a number of ways. You can change how you draw it in the original CAD package, and you can scale it on import to the "slicer" package. I need to do some calibration of the prints ours does, but have not felt like spending the time or material. So far it appears the scaling error is small enough not to matter on parts of this size.

Scaling is probably more used for material shrinkage..?

If you wanted to change dimensions you'd just go into the model and change the dimensions.

Working with plastic molds you have to factor in the shrinkage and machine the mold to account for it. They have shrinkage factors for all plastic materials in a plastic engineering handbook.

 

[Chris-PA]

Scaling is probably more used for material shrinkage..?

If you wanted to change dimensions you'd just go into the model and change the dimensions.

Working with plastic molds you have to factor in the shrinkage and machine the mold to account for it. They have shrinkage factors for all plastic materials in a plastic engineering handbook.

Yes, for sure, but this is not like puoring hot plastic imto a mold. The extruder head is driven to a series of XYZ coordinates, and the material is cooling as it goes. So partially the effect is larger voids between strings. And some of the error is just mechanical scaling error of the mechanism.

 

[Jimbo209]

Looks good. Where do I order a batch of 2100 air filter lids? Maybe someday they will be able to produce rubber or elastomer parts. A/V bushings for the early saws are getting scarce. Sure be nice to get a set of Echo 610 buffers, or 032.

or what about some 044 handles or inserts to convert flippycaps

 

[Stihlofadeal64]

or what about some 044 handles or inserts to convert flippycaps

Yeah! Bring it on! I'm in the market!

 

[Derf]

Very cool. What model printer are you using?

 

[scallywag]

inserts to convert flippycaps

Yes please!!