Carb Tool

This tool was spawned from a need to tweak the carburetor on my Craftsman 25cc, gas trimmer. I bought the trimmer from my brother in order to take care of the back forty, and he wanted the new 32cc version which just happened to be on sale at the time. It's been a great trimmer and all of the attachments for it work great, too.

Here is the story of how this tool came to be...thought I would share for the fun it was.

This little jewel ran great for a couple of years, on top of the years my brother used it, so it has some mileage. It always started first or second pull and ran like a scalded dog. I got it out this summer because the blackberries were trying to take over the planet...but it wouldn't stay running, except with the choke on and barely even then. Being the Old Wrench I am, I cleaned the air filter, changed the gas, put new fuel lines and a tank filter on and even put a new spark plug in, all to no avail. It just wouldn't run right.

After pulling the carb off and checking it, I realized it had two adjustment screws at the base. The two screws are for low and high speed adjustments, but they didn't have any slots or Phillips to adjust them...they were splined knobs and made this way so as to keep normal people from messing with them. Obviously I wasn't one of those normal people so I went on the net to see if I could find a tool or something; there was one on E-Bay for ~$15. However, still not being normal and having blackberries to tame, I went to the Mini with a piece of 3/8" Delrin and whittled one out that pressed on to the splines and fit into the surrounding housing.

Back to the carb...I cleaned it all up and put it back on, then set up my new tool on the low speed jet and sparked her up. Nothing I did would allow it to run without the choke on. Ok, Then...Plan B.

On the Sears website I found a forum about this model...turns out you can't get parts for the carb, but you can order a Brand New one for $30...Such a Deal, especially after the half day I spent so far and didn't even whack any Blackberries yet (thank goodness though, because the afternoon turned hotter than Blue Blazes!) I ordered one up; it arrived a few days later.

With a new carb installed and primed she started on the third pull. Whoohoo! She ran a little rough so I let it warm up and hit the throttle a few times...Ran pretty good, but I had a feeling things still weren't 100% right.

It went through the Blackberries like butter and then proceeded to trim a few dead limbs with the pole saw attachment, then on to whack down some "Stink Bushes" , (don't know what they are called but they smell like creosote). They wanted to take over, so out with the brush cutter attachment, and down they came. This was several hours work, off and on with water breaks. Toward the end though, the trimmer started to die out at idle. It would start back up fine and then die again after a little more cutting. I adjusted the idle but it was still a little rough so out came my trusty new tool and Wha Lah...ran like a top again, sounding happy and strong. The carb must have needed to settle in a bit, plus I ran her pretty hard that day. Since then, it continues to run strong and proud and always starts on the first or second pull. What a great little trimmer and now I have a trusty tool to dial her in if she needs it...thanks to my Mini!

Epilogue:

Turns out my brother's 32cc gives him trouble regularly and he still wishes he hadn't sold the 25cc. (He's actually the one who told me about getting the fuel line kit for it as he has changed his several times.) So to ease his tensions with the 32cc, I built a tool for his fleet of gas tools...turns out most of the adjustment screws for chain saws and trimmers are all the same. Note: the tool in the pictures is actually the tool I built for him...mine isn't nearly as pretty. ;-)

Now, as I think about this story, a truth comes to mind about good machines and how when you find them they just work and seem at some level to be happy with their jobs, and keep working. I probably could have bought a new one for the time I spent on this. However, when a good machine goes and goes and gives you all its got, I have always tried to give them a long life by fixing them and regular maintenance. I have also always listened to and talked to them, making both of us happy in our work. My Mini is quickly becoming...a fine machine with personality! It's what I call good Carma...

So, here are some pictures, detail of the tool and its making...basically on the fly.

The tool is about 3.5" long made from 3/8" Delrin. It's made like a nut driver so that it fits over the little flange piece and fits snug in the ID of the casting (Bottom Picture) surrounding the adjustment screws. It is also one of my first attempts of knurling with a Knurling tool from LittleMachineShop.com. The fine pitch Knurl didn't come out as good as hoped, but sufficient to grip it with the thumb and index finger. Small diameter Delrin really wants to flop around as you apply pressure for knurling and I had already made the tool, so couldn't use a live center on it. Next time I knurl Delrin, I'll knurl first, using a live center and as close to the chuck as I can get...then continue with the project. I am practicing my knurling skills and working on a spreadsheet; there will be more to say later, on another page.

This end view shows the press fit for the screws. I did this in 5 steps starting with a center drill and working up to a #8 or #9 drill and checking fit several times while getting close to what I wanted for the press fit. Keep in mind that Delrin will spring back after drilling so it's ok to go oversize just a skosh. This size left a nice score on the ID of the tool, and was achieved by carefully inserting the tool in the same splines over and over again. Kind of a Poor-Man's Broaching. Now when you put the tool on, if you lightly and slightly turn it, it finds the splines, then you can push it on.

Pretty simple tool really but works great and filled a need. I also think it will last quite a while because it is not needed often, but when you do, Whoomp, there it is...another useful thing made on the Mini, in short order. :-)