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MachinistBlog.com

Plans, projects and how-to's for home machinists

Wrench/Hammer Combination Tool for Mini Mill

By Roger Leete

This tool was made for my Grizzly G8689, but it can be adapted to almost any mill.  Just choose the right sized socket for your particular drawbar.  Note that I did not come up with this idea, but found it on the web.  I made the parts based mostly on the materials at hand.  Dimensions are mostly made up on the spot, and measurements were all made with a scale.  In other words, this project requires no careful measurements or has any critical dimensions.

Socket

First step is to find a deep well socket that fits the drawbar.  For my mill, that means 17mm.  I bought sockets at Harbor Freight, but just about any cheap deep well socket will do.  HF has them for about 2 bucks.  As you can see from the pictures below, I cut about 1/2-inch off the drive end, simply parting it off at the line on the socket.  (Some sockets have a different appearance, so roughly 2-3/8-inch long) This dimension is by no means critical.  I was worried that the sockets may be hardened, but a standard HSS parting blade cut it cleanly and easily.  This operation was done on a 7×12 mini lathe, so it’s not like you need an expensive machine to part off.  When you break through to the square bore it will be an interrupted cut, so take it slow at that point, or finish with a hacksaw.   Tip: get or make a carriage lock for your lathe.  It makes parting so much easier.

Next operation was to bore out the square drive hole.  Once again, this was done on the lathe.  The square hole makes for an interrupted cut, so take it slow and easy until you get it round to avoid too much impact on the tool bit.  Drilling first may be easier, to remove the bulk of the material.  You want to bore it out enough for the inner filler piece, but leave enough wall thickness for strength.  My bore is about 5/8-inch diameter, but this is not critical either.  I purposely made the bore tapered slightly.  I’ll explain why in the next step.  Set your compound over a degree or two, and bore it out to size.  The socket machining is done for now.

As purchased on the left, machined on the right

Next piece is the inner filler.  I made mine out of brass for weight, and because that is what I had on hand.  Steel would also work, but I’d not recommend aluminum as you want more mass.  This piece is slightly tapered the same as the bore.  The reason for this is to have it jam up into the socket to facilitate tightening of the hammer head.  Once turned to size, drill and tap for the hammer head screw.  I used 3/8-16, but 1/4-20 would work just as well.  You want enough thread to hold securely, but if you go too deep, you’ll be tapping into the side of the screw when you make the handle.  Using a hacksaw, cut a screwdriver slot in the opposite end. Continue reading Wrench/Hammer Combination Tool for Mini Mill

CNC Machined Tape Dispenser

This tape dispenser was made by the Advanced CNC class at Laney College in Oakland CA.  It’s made from a pound of 6061 aluminum and every part was made using CNC.  Click on the picture or this link to see more pictures.

Retractable pen made from 30-06 bullet casings

I think this is a cool project and the video may teach you some new machining or fabrication methods even if you don’t want to make a retractable pen out of a couple of empty 30-06 bullet casings.

The pen looks like it’s pretty easy to make.  The hardest part might be getting a couple of bullet casings without spending much.  It looks like you can buy small quantities of used cartridges on Etsy for less than $10.  You might want to also try asking nicely at your local gun shop or on Craigslist.

You may also have trouble finding the exact same pen if you’re in the US.  I’ve never seen one like it and the designer is working in millimeters, which means he’s probably in Europe or Canada.  But if you’re able to play with machine tools then you probably won’t have any problem finding a good substitute.

By the way, it looks like he made it on a 7×12  mini-lathe, which are pretty affordable and popular with home machinists.  I’ve got one and really like it, and I still use it a lot even though I have a bigger and better lathe now.

My First Attempt at Making Machinable Wax

I tried making some machinable wax last night.  It’s supposed to be harder than plain wax and mine wasn’t, or at least not noticeably.  But I believe I can fix it by re-melting it and dissolving more plastic into it.

Machinable wax is made from ordinary paraffin (candle) wax that has HDPE or LDPE plastic added to it to make it harder, more dense and to raise its melting temperature.  I used HDPE that came from milk bottles.  The ratio of wax to plastic is about 4 to 1 and I heard you could achieve that by just adding plastic to the wax until it won’t absorb any more.  I did that and then used my electric fryer’s basket to strain out the extra.  I realize now that the basket had too much undissolved plastic in it and that I probably should have waited more patiently and stirred the mixture more.

Here are some tips if you want to try making some

  • I used 2 pounds of wax.  I think it was just about the right amount for the 9×9-inch non-stick baking pan I used for a mold.  Although it could have held more.
  • Both my grocery store (in the canning section) and local Hobby Lobby store sold 1-pound packages of paraffin wax for $4.  But Hobby Lobby also had 10-pound slabs for $15 ($1.50/pound).  They also occasionally have their candle making supplies on sale and they sometimes have 40%-off almost anything coupons.
  • Machinable wax has many uses.  I was going to give this batch to a maker/hacker space for their members to use to practice machining.  Machinable wax won’t damage cutting tools, it doesn’t create sharp swarf and it can be re-melted and reused.  It’s also often used to make prototypes, molds, lost-wax castings and to test CNC programs.
  • I wanted to dye my machinable wax a fairly dark blue like you see in the picture.  But when it cooled it was a much lighter blue like the spilled wax on the cardboard.  I bought my dye from Hobby Lobby, which only offered one choice, a pricey ($5) package containing small amounts of red, yellow and blue.  I used up all the blue on just this one batch.  I’m going to find a candle making forum and ask the experts where I should go to buy more.  I also want to ask them if copper pipe would make a good mold for round wax rods for the lathe.
  • DO NOT try to use food coloring to dye your wax.  It contains water and when you add it to the melted wax it will boil and spit creating an unsafe condition.
  • DO NOT melt your wax over an open flame because it’s very flammable, especially before you begin adding plastic to it.  And DO NOT use any kind of heat source that you can’t easily and precisely control the temperature of.  Many people make wax candles and it’s not a particularly dangerous hobby.  But if you aren’t careful you can burn your house down and/or severely burn yourself.
  • You should have an accurate way to measure temperature because pure paraffin wax can burst into flames at 390° (F), although its flash point will increase as you add plastic or other additives to it.  Candy thermometers usually cost less than $10 and a non-contact infrared thermometer, which is what I used, can be purchased for $20-$30.  I was very cautious and never let the mixture get hotter than 290° because I was making it indoors.  I may have turned the temperature up more if I’d been making it outside in my driveway.  By the way, paraffin wax melts somewhere around 125° to 165° and HDPE melts at about 266°.  The flash point of HDPE is about 650°.
  • I wore protective clothing and safety glasses to protect myself in case I spilled any wax.  I also wore welding gloves when I poured the wax into my mold.
  • I saved plastic milk bottles for a long time to get enough HDPE.  I used scissors to cut them up and I didn’t even try to get their paper labels off.  I just cut them out and threw them away.  Many other containers and bags are made from HDPE and you can identify them by looking for the triangular recycling symbol they almost always have.  It will usually tell you exactly what kind of plastic it is made out of.  If you want you can buy HDPE from Enco and other machine shop supply companies.  They will probably call it “High Density Polyethylene.”

Random Quote

Hatred is blind, as well as love.

— Oscar Wilde