To start off my titanium mechanical pencil build, called wrTie, I decided to teardown a number of different mechanical pencils for inspiration and design ideas. I find the mechanisms in mechanical pencils very interesting. I also find the manufacturing processes that are used exceptionally interesting.
Here is a teardown video of my favourite mass produced mechanical pencil: the Pentel P209 (0.9 mm version). The Pentel P20x series (there are 0.3, 0.5, 0.7 and 0.9 mm models) has been around for a long time. It is exceptionally well made given the price point it is hitting and the parts involved. There are 12 parts in total, including 5 fully machined parts. A number of the parts require plating. There are 2 parts that are molded out of plastic. And then it has to be assembled! You can buy a Pentel P209 for less than $5 in the United States and less than $7 in Canada. That’s actually pretty crazy considering this pencil contains machined parts and even more so once you consider that Pentel is probably selling it to it’s retailers for less than half of what they are retailed for.
The heart of the Pentel 200 series is a removable fully contained feeding cartridge. The cartridge features a number of machined components in the feeding mechanism. The components are probably massed produced on swiss style screw machines (a lathe but instead of the carriage moving the spindle moves in the Z direction – often called sliding headstock machines). These machines could be cam actuated screw machines or they could be CNC controlled units. CNC swiss style machines, like the ones produced by Star or Citizen, are really interesting machines. Here is a video of a Citizen L20, one of the more popular CNC swiss machine that you will find today:
The Pentel P209 cartridge has been used in a number of titanium mechanical pencil builds on Kickstarter. I can’t confirm it directly as I haven’t purchased one, but check out this project (you have to scroll about half way down and you’ll see a picture of what looks to be the Pentel cartridge: https://www.kickstarter.com/projects/cogent/titanium-mechanical-pencil-and-titanium-pen. Given the Pentel’s design, you could easily make a new mechanical pencil by machining a new outside body for the Pentel. I won’t be doing that because I think it is too easy!
After getting confused as to what podcast they are recording, Max and Justin talk about hauling machine tools home. Of course the stories keep getting better and more ostentatious the more they are told. We also talk about:
Max’s work on his Trent Pinion mill
Change gears on the lathe – you don’t need that 127 tooth to cut metric threads all the time. Max finds a really well done gear calculator on the internet: http://geargenerator.com
Justin gets a Delta Rockwell surface grinder for the home shop and tells the story about dragging it home in his father in law’s truck
Max can’t be outdone: 7 Hjorths, an overloaded van, pouring rain and a flat tire
Any other Hjorth owners out there? Send us some info!
If you live with someone engaged in the home-shop machining hobby, and you are responsible for any domestic duties involving clothing, you have no doubt found swarf in the laundry. Just the other day, I shook out one of my husband’s sweaters he had worn in the shop, and a cute metal corkscrew resembling a tiny clock spring (no, my husband’s chips don’t always come off in perfect “9’s”) bounced on to the floor. Our children thought it was cool. We then examined a knit sweater that had been worn in the shop and noted several metal chips embedded in the weaves. The next 15 minutes were spent scouring the house for magnets to see if we could pick-up the sweater. It didn’t work, but the exercise ranked higher than our children’s 1 hour allotted TV time for the day.
I could start to nag at my husband for all the chips he is tracking in to the house via socks, sweaters and hair, but have thought better of it. I have observed that the machining hobby has provided an interesting (and even productive) outlet for my husband’s creative energies and stress, while also providing many learning opportunities for our children, and even myself.
The video documentation of this hobby and its results via YouTube has also provided interesting learning opportunities for our family. Its cute to watch the children excitedly bring other family members and friends to the computer screen to show them what Daddy is working on in the shop right now. Our son has even started making his own videos with his V-Tech video camera of his Lego constructions. This has been a great lesson to my husband and I to never underestimate the impact you’re having on those little eyes watching you.
Yes, it would be nice if I could park my car in the garage and Band-Aids weren’t a standard weekly grocery item. But for all its benefits, I guess I’ll put up with the swarf in the laundry.
Megan is the wife of Justin. She has the pleasure and the pain of dealing with a manufacturing gearhead on a daily basis.
Max and Justin invite Dan Sherman on for some general shop talk. We started talking about what is going on in the shop but in true home shop machinist fashion this episode heads off on several slightly off topic tangents. Within this episode:
Welding and machining, is it a left brain right brain sort of thing?
If you are depressed about what is in the news just listen to this podcast and you won’t have a chance to listen to the news again! In the longest episode to date Max and Justin talk about 10 tools that we find essential to our shops. Buried within this episode:
As usual Justin forgets to edit something out that Max says
Max tells us more about his Trent Pinion Mill that arrived from the UK via some sort of beaming machine
Gearotic and Max’s Orrery build (say that without sounding intoxicated!)
Why the Brits put the carriage wheel on the right side of the carriage
Maintenance on cars, 3D printers, and terrible instructions
Max tells a joke
Fecal material on cell phone screens
The 10 tools in the shop that we find useful … which turned out to be 8
I spent 30 minutes on a Friday evening making up something that has been on my project list for awhile. I made a swarf separator to go in front of the vacuum. Often these are called dust cyclones, or particulate cyclones, or separators of some sort. I made a video of how I constructed it (which took longer than actually making the separator):
The design is very simple. The pail itself was from someone with a pool – it was used to hold bromine (I love re-purposing stuff!). I’ve been saving the pail for this for awhile because it has a nice tight fitting lid. I cut 2 holes in the top for some 1 1/2″ threaded ABS couplings and a 1 1/2″ to 1 1/4″ bushing found at a local hardware store. One coupling was male threaded and the other was female threaded. The 1 7/8 Ridgid vacuum hose fit well onto these couplings after I turned them to fit. A long 1 1/2″ ABS elbow was used to direct the dirty suction flow along the side of the container. The ‘clean’ air comes out the centre and into the vacuum.
I immediately tried it by cleaning up the lathe. It worked very well for metal chips. I’m not sure how well this design would work with saw dust – something I’m bound to try out at some point. I don’t do that much work with wood, and when I do it generally is general construction – which usually happens outdoors.
I was considering purchasing a Dust Deputy – a purchased cyclone attachment for standard vacuums. They are $60 for just the cyclone (still requires a pail with a lid) or $135 for a cyclone, pail, lid and hose. Lee Valley also has their Veritas cyclone lids for larger containers for about $50, but I prefer the 5 gallon pail size.
I have about $30 into the project including the hose (the most expensive part of the project), which isn’t too bad at all. Now I won’t fill expensive vacuum bags up with metal chips anymore, and I can keep the vacuum bag for filtration of fine particulate like grinding dust.
I didn’t make drawings for this project because I thought it was very simple. If you really would like something, send me an email and I’ll try to do something up.
I needed to be able to bore some holes using the lathe as a mill / drill press for a number of upcoming projects. My 10×18 lathe has a MT4 spindle taper. MT4 is a bit of an odd ball taper for a lathe. It’s not quite big enough to accommodate the 5C taper or the R8 taper – both of which plentiful amounts of inexpensive new and used tooling is available. The X2 mini mill I have uses the MT3 taper – so naturally it made a lot of sense then to make up an adapter to go from MT4 to MT3, as well as a drawbar and associated hardware to go along with it.
Here is a video of the project:
The threaded drawbar itself was made out of some mystery metal in the shop. It was interesting stuff with a really hard outer layer that through hot chips all over my arm when I was turning it. It almost made me want a lathe with a carriage wheel on the right side of the lathe. The drawbar was turned between centres to within .001″ over 10″ – something I was happy with. It highlighted my need for a travel steady – I’ll have to add that to the project this.
The MT4 – MT3 bushing / adapter was made out of an inexpensive MT4 – MT3 adapter that would be commonly used in a drill press. I cut the tang off with an angle grinder and cleaned it up on the belt sander. I was thinking about making it up entirely, but I wanted a hardened bushing.
The video marks my tenth video that I’ve done, and it also incorporates some significant changes in how I put them together. Going forward I hope to continue to improve the quality as I learn.
The titanium pencil project is also still very much a going concern – I hope start some tear downs over the next few weeks to start the project off. Many of the projects I’ve been working on in the shop are laying groundwork for the build. So in short – stay tuned!