Instructables
Picture of Give a Boston Model 18 a Second Life
This is our 30-year old Boston-Hunt Model 18 electric pencil sharpener. Its present incarnation is as an X-ACTO 1818. It suddenly quit working. This Instructable will not show how to repair it, but to use its parts for a pencil sharpener powered by a battery drill. 

Tools
  • Screwdriver
  • Measuring rule
  • Saw
  • Drill and bits
Materials
  • 3/8 inch plywood
 
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Step 1: Disassembly

Remove the tray that catches the pencil shavings. Remove three screws on the bottom of the unit as in the first photo. Remove the mechanicals from the case. The second photo shows what the problem is. The large plastic drive gear has become brittle and has broken. Remove the two screws that attach the cage supporting the cutter as in the third photo. Pull the cutter out of the machine.  

Yes, you can buy a parts kit that includes a new drive gear and a new cutter assembly. But, the cost is almost identical to the cost of a new pencil sharpener.

Step 2: Build a support

Picture of Build a support
The shaft on the cutter assembly can be grasped by the chuck on a 3/8 inch electric drill. The space between the shoulder on the geared plastic collar and the end of the drill chuck is a tiny bit more than 3/8 inch. Get a piece of 3/8 inch plywood and cut a rectangle 2 x 2 1/2 inches. (2 x 3 or 3 1/2 inches would have been better in retrospect.)


Step 3: Drill

Picture of Drill
Drill a 1/2 inch hole through the plywood that is located 5/8 inch below one long edge and centered between the two shorter edges. Because I was using a spade bit, I drilled part of the way through and turned the piece over to drill the rest of the hole from the other side. This eliminates chipping the wood surface.

Step 4: Two more holes

Picture of Two more holes
IMG_0709.JPG
Notice the two tips on the geared plastic collar. Mark where they touch the plywood piece. Drill two 1/8 inch holes. See the second photo. Press the geared plastic collar into the plywood. The tips are a little off-center and will go into the plywood only one way. Round the corners for aesthetics.
spikeseller2 months ago
You have some excellent posts on this site. Thank-you for great posts. I love my Boston 18. There is no substitute for its ability to sharpen a pencil. Boston does not support this unit with replacement parts. You can buy a replacement gear on eBay for about $10(US). A guy casts them out of acrylic or nylon (I think) specifically for boston sharpeners. It is blue instead of white, but works great and after 1-1/2 years of use has no visible wear to speak of. It my not last 25 years like the original, but it may still outlast me, which is my objective. I would actually like to see an instructable on how to make the gear, but I do not have the expertise. If I had not found the replacement gear I would use your setup for sure. A sharpener of the quality of the Boston 18 can not be found today, at least not for what I am willing to pay for a sharp pencil:)
Phil B (author)  spikeseller2 months ago
Thank you very much for the information. Others who look at the Instructable will see what you posted and many will be helped by it.

I thought about ways I might be able to use the old gear, although broken into two pieces, to cast a new gear; but, gave up. It is likely possible, but beyond what I have available.

I am not very demanding and was ready to use my solution for our household needs. My wife was not really satisfied with that approach, and we now have a new electric sharpener from Costco. Although it got mixed reviews on Amazon, it has worked well for us. I use my adaptation of the parts from the Boston 18 in my garage workshop.
Bill WW1 year ago
I took my Boston #18 sharpener apart planning to use the motor and gearing to automate a new table saw rip fence. The fence is complete, it is great. But the motor drive has not happened yet. Still have all the parts.

Bill
Phil B (author)  Bill WW1 year ago
That is an interesting idea. The broken drive gear was once white, but yellowed badly over the years. That signals a change in the strength of the plastic. It would be better if the gear was at least pot metal. (Do not give up on the idea of welding, yet.)
stroland1 year ago
Not only can you sharpen pencils again but you saved a little land fill space and exercised your brain. Good job!
More than likely it works far better than the original.
John
Phil B (author)  stroland1 year ago
John, Yes, some landfill space was saved, and it does work as well or better than the original. I am surprised how well it works without sending pencil shavings in a wide pattern.

When ours quit working I looked on the 'Net for parts at a favorable price. I found a surprising number of people looking for the same plastic gear. My hope is that in time people who need that gear will find this Instructable, and it will be an acceptable alternative for at least a few of them.

I looked at your profile and saw that you want to learn to weld. Perhaps you have already found the Instructable I did on learning to weld. There are people who used some basic instructions and practiced until they were welding. That might not work as well for special metals requiring special procedures, but it works pretty well for home DIY types who plan to work with only mild steel. 

Thanks for the comment.

Phil
Yes, I want to learn to weld, and surf (not really), and build my own camper, and etc. then I realized that I will be 70 in 10 days so I thought maybe I need to forget a few of these things. Then I saw Diana Nyad yesterday completing her swim...no way! I am sticking with my goals and adding some more. On tap this afternoon [after I finish tiling in my bathroom (75% done)] is to do your pencil sharpener mod. I have the same model with the same problem.
Hello John, Phil thinks I should take up welding also. I will be 72 in two months, so have a head start on both you and Phil.
Bill
Phil B (author)  stroland1 year ago
Happy Birthday, early, John!! I am about 2 1/2 years behind you at 67 years, 5 1/2 months in age.

I got a welder about 13 years ago and have never regretted it, only that I did not do it earlier. You will find plenty of uses for a welder in the years to come.

I was a Lutheran pastor for 40 years. I do not need to do these things, but I read a couple of chapters from my Greek New Testament each day, I spend 30 minutes or more trying to learn the biblical Hebrew that I never really used as I ought to have, and I work on my German with readings and Podcasts. I never expected to do it, but I found it necessary to produce and give a sermon in German twice since last November, even though I am retired. I feel pretty good about being able to give sermons in German because I did not speak German at home and had only a couple of years of it in school. I learned a lot of it listening to shortwave radio and reading a contemporary German Bible. I also have a stack of books I always intended to read, but have not yet. I try to read some each day. Not only do these activities keep me busy, but they are good mental exercises until dementia finally sets in. By any standard, I could have put all of these things aside and merely vegetated when I retired a year ago.

I am glad to know you can make use of what I did in this Instructable. The dimensions of the plywood are not critical, except for the 3/8 inch thickness. A wider base dimension makes it more stable and less apt to rise off of the table when you push the pencil harder than necessary. I made the vertical dimension enough to raise the front of the drill keep the drill chuck from rubbing on the table. A little incline upward on the drill is also good for holding the pencil more comfortably. I should have been more careful when I drilled the 1/8 inch holes for the pins that keep the plastic collar from spinning. I had to make the holes a little egg shaped so the pins would fit the holes. More precise location and drilling would have eliminated that.

Let us know how it works for you.

Phil

I would have just have just bit the cost to fix it. Don't think they're as well made as they used to be.
Phil B (author)  explosivemaker1 year ago
We were saying the same things about how well they were made thirty years ago when we bought this one.
Phil B (author) 1 year ago
The drill connects quickly, so there is no sacrifice.
Put a crank on the shaft instead of the drill then you'll have a sharpener without sacrificing your drill