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MachinistBlog.com

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

Review – $40 QCTP for 7x Mini-Lathes

This is a review of a very inexpensive Quick Change Tool Post (QCTP) set for 7x mini-lathes that can be purchased on Ebay for about $38 (including shipping).  It is considerably less expensive than similar size QCTPs that you can find on LittleMachineShop.com and Amazon that cost about $135 to $155 plus shipping.

I purchased it because the cut-off blade holder for my 10-year old A2Z CNC QCTP had broken and I needed another one ASAP.  I didn’t have time to fix it and I couldn’t buy a replacement because the company has gone out of business.  My set was on loan to the SparX 1126 FIRST Robotics Team, where I am a mentor, and it was getting heavy use because we were in the middle of the build season.

So, when I came across this cheap QCTP set on eBay I decided to take a chance and buy it for the team.  The same set is sold by many eBay vendors and I chose this one and paid a higher price, $45, because they were promising delivery sooner than most other vendors and the seller has a high rating.  It was delivered six days after I ordered it.

It’s manufactured in China and it comes with four tool holders – two identical holders for turning and facing bits, a ⅜-inch boring bar holder and a holder for ½-inch cut-off blades.  The tool post is made almost entirely from hard anodized aluminum and the tool holders are made of steel.  In comparison, the $135 QCTP that Little Machine Shop sells for 7x lathes is made entirely of steel and it includes an additional holder that can knurl in addition to hold another tool bit. Continue reading Review – $40 QCTP for 7x Mini-Lathes

My Lulzbot Mini

My Lulzbot Mini with LED strip lights that I added. The object on the bed is half of an exhaust adapter for a laser cutter.

I started the Rochester Makerspace more than 2-1/2 years ago. It’s a non-profit (501c3) community workshop and art studio in Rochester New York that provides low cost access to sophisticated tools, teaches classes, organizes events, and hosts school field trips.  The makerspace has many very hard working volunteers but it’s still a nearly full-time job for me.  It’s also unpaid one so I also have a very demanding full-time day job.  That’s why this website has been so dormant.

Ironically, I don’t get a chance to make anything anymore because I’m so busy all the time.  That was really starting to bother me so last spring so I bought a Lulzbot Mini 3D printer.  It conveniently sits in my home office so I can make something once in awhile.  It’s a great machine and I want to to tell you about it in case you’re looking for a really good “hobby-class” 3D printer.

The Lulzbot Mini costs $1350, which makes it one of the more expensive 3D printers in its class.  But I think it’s worth the extra cost.

  • To get a high quality 3D print your bed needs to be perfectly level and your nozzle has to start at the proper height about the bed.  Most current machines (all?) require you to make those adjustments manually and you have to periodically redo them.  The Lulzbot eliminates that chore because it has a self-leveling bed.  It measures the height of the four corners of the bed before every print and then automatically compensates if it’s not level. I won’t try to describe exactly how it does that but trust me, it works great.
  • Most printers also have a problem with getting ABS plastic to adhere to the bed consistently.  So their owners resort to all kinds of tricks, like using hairspray, glue sticks, large skirts, or a mixture of acetone and plastic. Many people avoid the problem completely by only printing with PLA on a layer of blue painter’s tape.  The Lulzbot Mini doesn’t have this problem because its heated bed has a layer of PEI. It’s a plastic that ABS sticks very well to when it’s hot and comes off of fairly easily when the bed cools down.  As a result I print almost everything with ABS because of its extra strength and durability and because it’s just so easy with the Lulzbot.
  • I also bought the Lulzbot because I wanted to be able to print with Nylon, which is something most 3D printers can’t do.  The Mini can do it because it has an all metal extruder that can reach the necessary temperature.
  • The Mini also produces very high quality prints.  I’m not sure I remember correctly, but I think it came in second in Make magazine’s latest 3D printer tests.  It’s also super easy to use.

I also think the Mini is very well designed and durable.  It’s also an open source design and you could download all the files and information you need to build one from scratch.

There are a couple of things that I don’t like about the Lulzbot.  It’s too noisy when it’s running.  The Rochester Makerspace has a couple of Soldoodle 3D printers and a Rostock Delta we built ourselves and they are almost as quiet as a whisper.  I also think the cost of some of the Mini’s replacement parts are too high.  The two parts you’re most likely to need to replace someday are the cooling fan on the extruder and the PEI on the bed.

The Mini comes with a one-year warranty and I know first hand and from others that the company provides very good customer support.  The PEI on my bed was badly damaged by someone who used a screwdriver to pry a print off of it when I wasn’t looking.  I needed to fix it within 2 days for a demonstration and the company very nicely agreed to ship a replacement overnight at no extra cost.

If you don’t know what you can make with a 3D printer then check out Thingiverse.

I’m not sure when I’ll be able to contribute something else this to this website.  The Makerspace is getting closer to being able to hire some staff members, which will make my life easier.  I may actually be able to do some machining again.

I want to thank Mikey and Roger for continuing to help visitors to this website who have questions or need advice.

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

Update

I feel like I have three full-time jobs. In addition to my day job and I’m working another 20 to 30 hours a week trying to get a nonprofit makerspace started in Rochester NY. My wife and I are also taking care of her father, a widower, whose needs constant care because of failing health. And we’re helping to take care of a daughter and her family. She’s just had surgery for the second time this year to repair a heart valve.

So I’m tired and stressed, but not nearly as much as my wife, who shoulders most of the burden of taking care of family members. I help too, but I mostly take care of our pets and our granddaughter. She is a genuine saint because but she has continued to be very supportive of the makerspace. She understands that I can’t stop working on it because many people are now counting on me to follow through with what I started.

I launched the website for the Rochester Makerspace in mid-May and we now have many supporters, seed money, tools and a dedicated group of volunteers. We still haven’t rented a space but we’re actively looking for the right one. I expect that our doors will be open within the next couple of months and maybe as soon as a few weeks.

I’ll be even busier for a while when that happens. Although I expect my workload to taper off as we figure out the best ways to manage the space. The health problems of my father-in-law and stepdaughter will also end.  So there’s a good chance you’ll see me regularly working on MachinistBlog again someday.

If you’re wondering, the CNC router I’ve been building for more than a year is still not finished, although I’m continuing to work on it. I obviously don’t have much spare time and when I do I’m usually so tired that I’m either unproductive or I make stupid mistakes.

But I’ll bet money that it’ll get finished because it’s going to have a home in the makerspace and there are others who will help me with it.

Thank you Mikey and Roger for answering the questions that Machinistblog’s visitors leave in the comments or on the forum.

Random Quote

Truth is more of a stranger than fiction.

— Mark Twain