By NateD, on July 1st, 2010
Jan Ridders has updated plans on his web site for two of his favorite engines: a 2-cylinder flame eater and a Scuderi Split Cylinder internal combustion engine.
The flame eater was one of the first engines that Jan drew up detailed plans for and one that has received a lot of interest since he first made it eight years ago. He said the quality of these original plans was poor and in his spare time has updated the CAD drawings to make them clearer. It was a project Jan said he almost scrapped because at the time he didn’t know much about what it took to get flame-eaters to run, but after building a vertical 1-cylinder engine he got the hang of it and picked this project up again.
The Scuderi Split Cylinder engine was another of Jan’s favorites, but after the plans raised design questions he decided to update the CAD drawings. Jan found plans for it on the internet and then made some variations, like separating the two cylinders entirely. This is easy to make using mostly standard parts.
Jan features a number of other engines on his web site, which is available in both English and Dutch. You can request a copy of his plans by filling out this short form.
By Rob, on June 30th, 2010
Pete Stanaitis has designed a really nice drilling and tapping block and you can find the plans for it on his web site. A tapping block is a simple but very useful tool used to make sure a tap is started straight in its hole. The tap is much more likely to break if it’s not, plus you’ll probably get poorer quality threads even if it doesn’t. Pete’s block can be used with 16 different sized taps from size 6 to 1/2-inch (NC & NF threads). It can also be used to drill straight clearance holes. You could make the block using aluminum or another kind of steel, but it will last longer if use 4140.
By the way, Pete is a blacksmith and has a large web site with lots of interesting and useful information.
By Rob, on June 26th, 2010
The folks over at IH CNC & Machinery have a nice set of instructions for building a wooden bench and enclosure that can handle the weight of a 1,250-pound mill. It is also designed to contain and drain away coolant, which is why I may be building a smaller version soon for my CNC mini-mill.
The mill sits in a particle board tray lined with inexpensive plastic shower pan liner which you can buy at your local home improvement store. A sidewalk drain is installed in one corner to collect coolant, which drains into a 15-gallon storage bin under the bench. The storage bin also contains the coolant pump.
The back and sides of the enclosure are made with the same galvanized steel used to make heating and cooling ducts. It sounds like a good, durable and inexpensive choice. But I’ve been wondering how well the waterproof panels you can buy at home improvement stores for making shower or tube enclosures would hold up to coolant. It seems like they might absorb sound better and the lighter colored walls would make the inside of the enclosure brighter. Any opinions?
The front of the enclosure is Plexiglas and has a door. It’s mounted in a frame made from square aluminum tubing and angles. The top is left open, which is not going to work for me. I want to enclose mine completely so I can store things on top of the cabinet, reduce noise from the mill as much as possible and have a place to mount fluorescent lights inside above the mill.
Their web site also has some other neat tips for mill owners. I also like their mills and I’m going to seriously consider buying one when I save up enough pennies for a bigger mill.
By Rob, on June 20th, 2010
I wanted to move the belt drive from my old mill to my new CNC mini-mill. Well, the spindle nut didn’t want to come off, which didn’t make sense because I didn’t have any problems putting it on six months earlier. I went looking for pictures and advice on the Internet and had trouble finding any. So I wrote this article.
My goal is to:
- Show you how quick and easy it is to install a belt-drive kit on a mini-mill.
- Discuss the advantages of using a belt drive.
- Tell you about a dumb mistake I made so you won’t do it.
- Briefly explain bearing preload and how it can cause your spindle bearings to get too warm after you’ve installed a belt drive or taken your head apart for some other reason.
The belt drive kit for my mini-mill was made by the Steele Company. It cost about $130 and you can either buy one them or LittleMachineShop.com. It’s pretty easy to install and will probably take about 20-40 minutes. You can also find plans and instructions on the net if you would like to build your own. If you can make a pulley on a lathe then it shouldn’t be too hard.
There are some good reasons for installing a belt drive:
- It will eliminate any chance of breaking a drive gear, which can happen pretty easily if your cutter jams. Instead of a gear breaking the drive belt should slip instead.
- It will increase the top speed of your spindle from about 2500 rpm to more than 4000 rpm, which is important if you use very small end mills or drills.
- Your mill will run much quieter.
- A belt drive may also make it easier if you ever want to mount a different motor on your mill.
Before you install your belt drive I suggest turning your spindle on as fast as it will go and walking away from it for about 10 or 15 minutes. Then feel or measure how warm the milling head gets. That’s about how warm it should get after installing the belt drive.
The bearings in my CNC mill’s head started running hot after I installed the belt drive because I tightened the spindle nut just a little too much. The more you tighten that nut the more “preload” you give your spindle bearings. You want to preload them enough to eliminate the internal play in them (which can cause run-out), but not so much that you cause excessive friction, heat and premature wear. The nut doesn’t need to be tightened very much and I only had to loosen it a little to fix the problem.
One thing you’re going to have to do is to unscrew the spindle nut on top of the head. There’s two things you need to know before you do that:
- It has a left-handed thread, so it’s going to turn it the “wrong” way.
- Before you start unscrewing it you need to loosen the set screw in it. That was my dumb mistake. Even though I’ve seen it many times I still forgot it was there because it was facing away from me when I inserted the pin to lock the spindle. Luckily, I stopped turning the wrench before I did any real damage.
Disclaimer: This is an overview. These instructions are not meant to replace the ones that come with your belt drive kit.
Continue reading → How-to: Install a belt-drive on a mini-mill
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