Update on my CNC router build

Don Druckenbrodt, owner of Nite Owl Guitars, built a Solsylva CNC router that's a little bit bigger than mine. He stained his wooden parts instead of painting them like I am. Click on the picture to learn more about his router and to see what he uses it for.

I took a week of vacation time just to work on my Solsylva CNC router.  My goal was to spend at least 10 hours a day on it and try to get it finished.  I had a very productive week but I spent most of it working on other things instead.  For example, I spent parts of four days getting work done on my car because  I usually have to rent one or take a vacation day if it needs service that has to be done during the day.  My Camry got new tires, a bad wheel bearing replaced and a front end alignment.   I also tried to get a minor EVAP (emissions) problem fixed at another shop but I got ripped off.  I didn’t find out until it was too late that the dozens of very positive Google and Yahoo reviews they had were fake.

I also spent about eight hours cleaning up my desk.  I can’t stand it when it gets real messy and it had acquired a mountain of paper because I’ve been extremely busy this summer.  Some of that time was spent calling up companies and asking them to take my name off their mailing lists.  I am amazed at how many of them will send you a monthly or quarterly catalog for years even you’ve never bought anything from them or you’ve maybe placed one small order.

We also had our driveway repaved because the one we had put in about eight years ago developed deep ruts where my wife parks her car.  I didn’t want to have it done during my vacation but I’d been trying off and on for a year to get it repaired.  I’d called at least four other companies (some more than once) and none of them showed up to give me an estimate.  I finally found a one that promptly gave me one and provided good references too.  So I wasn’t going to make them wait when the weather finally dried up enough for them to pave it.

Getting the driveway done hurt my productivity for much of the week.  I have so many tools in my small garage workshop that I’ve had to put most of the bigger ones on wheels so I can push them out in the driveway when I need more room to work.  I couldn’t do that because of the new driveway and that made it much more difficult to paint my router and its stand.

Painting has been holding up progress on my CNC router

Painting has frequently held up my progress and if I could do it over again I’d probably stain my router’s wooden parts like Don Druckenbrodt did.  One reason is my tendency to be a perfectionist.  I have it well under control most of the time but I struggle with it when I do painting, trim carpentry and some other tasks where appearance is important (or I think it is).  And I’ve been trying to do an especially good job on my CNC router because pictures of it are going to be on this web site and I’ll probably be taking it to some shows and workshops.

I always seem to spend too much time sanding and fixing imperfections in wood, which is why I don’t do much woodworking anymore.  I enjoy cutting and fitting the pieces together but I hate applying a finish unless it’s a simple project that just needs a little sanding and a few coats of Tung oil.  The metal parts I make in my home machine shop often don’t a require a finish and it’s usually pretty quick and easy to apply one if they do.  It usually involves just a little polishing, often with a Scotch-Brite pad, or a quick coat of paint from a spray can.

I don’t like Glidden’s Trim and Door Paint

I also chose the wrong paint and because of that I had to sand down my original paint job on both the router table and its stand and then repaint them.  I’m about to do it again to the table but this time I’m going use a different brand of paint.

I was originally going to use Rustoleum enamel which sells for about $9 per quart.  But I wasn’t real happy with its durability the last time I used it on wood.  So I looked around Home Depot and found Glidden’s “Trim and Door Paint.”  It cost twice as much but I decided to try it because it’s a “new” oil-based “gel” paint that is suppose to dry without brush marks or drips.  I won’t bore you with the details, unless you want to hear them, but I got a lot of brush marks and runs even though I carefully followed the directions on the can and watched the instructional videos on YouTube.  I blamed myself after my first try but after my second try I decided it was the paint.

It also took Home Depot more than two months to get me the “Rich Blue” I wanted.  Glidden’s Trim and Door paint can’t be tinted and the color I wanted was one of two they don’t stock even though they advertise them.  To be fair, they did try hard to get me the paint.  I ended up having to special order six cans and then they refunded the cost of the five I didn’t need.

Other things also interfered with my original plans but I’m not really complaining.  I had a very productive week and I got a lot of important things done.  The router just wasn’t one of them.

Grinding Lathe Tools on a Belt Sander - Part 3

This is the last article in Mikey’s series about grinding lathe tool bits.  In part 1 he discussed his experiences with grinding bits, why he uses a belt sander instead of a bench grinder and introduced some terminology about tool bit shapes and angles. In part 2 he covered tip geometry and tool shapes in more depth.  Here he describes the actual process of grinding a tool bit.

Grinding a tool

ALWAYS wear eye protection, hearing protection, a dust mask and leather gloves when grinding. No tool is worth sacrificing your body parts.

Remember, no angle works in isolation

Think about what you need with regard to shape, strength, tip access, and the type of material(s) you will use the tool on. Choose your relief and side rake angles and when you are clear on what you intend … just grind it that way. This thought process is illustrated below.

Let’s grind a general purpose right hand tool from a 3/8” HSS blank that should work with steel, aluminum, plastics and stainless. It is not optimized for any of these materials but should work fairly well with all of them. You can rough, face and finish by varying the lead angle of the tool. By choosing a general shape for multiple materials we need to think about the compromises these choices force on us:

  • The overall shape will be half-way between a rougher and a facing tool. To allow this tool to face into a shoulder we’ll give it an end cutting edge angle of 80- 85 degrees. This more acute angle reduces tip strength a little but is of no concern on a small lathe even when roughing, though it does add to the equation.
  • To reduce cutting forces we will use a conservative side relief angle of 15 degrees and a more aggressive end relief angle of 15 degrees; both changes will improve facing, finishing and edge penetration. In addition to turning you can also use this tool for chamfering with the side and end.
  • Since I am losing some strength by using greater angles for side and end relief as well as from that more acute end cutting edge angle, I’ll try to conserve some strength and compromise chip clearance a little by keeping the side rake conservative at 15 degrees. Back rake is at the high end of the standard range at 15 degrees to further assist the side rake in improving chip clearance; it also boosts finishing potential.
  • We’ll use a nose radius between 1/64” and 1/32” to allow a deep cut while still giving a fair finish.
  • A LH tool is the same except the shape is reversed.

As you can see, multi-purpose tools require some compromise. I have given more emphasis to tip strength because we will also be using this tool for roughing, which creates large cutting loads in harder materials. We’ll discuss this further in the End Notes.

General Advice:

  • If you are new at this I suggest practicing on mild steel key stock from the hardware store, not HSS. It grinds easily and is cheap. Just cut it to the same size as your HSS blanks so you get a feel for handling a bit.
  • Let the belt cut; you want to use only moderate pressure – enough to keep the belt cutting continuously – and keep the tool moving back and forth across the entire width of the belt. The steel will show you some color to indicate how hot it is getting. HSS can get into the low red range without compromising the steel but if I see anything beyond dark straw I know I am using the wrong grit, my belt is worn or I’m putting too much pressure on the tool when grinding. It the tool gets too hot to hold let it air cool or just set it down on a brick – it cools fast.
  • The usual sequence I follow when grinding a tool is to cut the side first, then the end, followed by the top. This isn’t written in stone. You can grind the top face first to ensure the top and side cutting edges meet exactly at the edge as they should – think about it.

Seen below is my grinding setup. It is a ½ HP Craftsman 2” X 42” belt sander with a custom steel table settable to precise angles. The platen is a 2”W X 9” L X 1/4” thick piece of O-1 ground steel to which a Pyroceram liner is epoxied; it is dead flat after years of frequent hard use. It is equipped with a 24 grit Aluminum Oxide belt, soon to be coated with a wax stick lubricant. This belt cuts very fast and very cool when using only light to moderate pressure applied toward the belt and I highly recommend it for shaping. Just ease up on the pressure as you near the end of the grind to eliminate coarse grind marks. After shaping, you can change to progressively finer grits and produce a near mirror finish if you choose.

The table is set to 15 degrees to cut the side relief angle, the vertical angle under the side edge. The side cutting edge angle is determined by the angle with which you present the tool to the belt; as you grind it you are grinding the side relief angle at the same time. For this tool the side cutting edge angle is approximated so that 60% of the side is ground off when I am done. If I want a rougher I grind 40% off the side, 70% for a facer and 80% for a finisher.

Continue reading → Grinding Lathe Tools on a Belt Sander – Part 3

Stepper Motors & Drivers for My CNC Router

I’ve been away on vacation which is why MachinistBlog.com has been so stale.  We only went away for one week this year but I always seem to spend the week before running around like crazy getting ready to go and then the week afterwards working like crazy to get caught up at work and with chores around the house.  If you’re wondering, wifey and I went to Washington D.C. and did typical touristy things which included visiting a lot of museums.  We enjoyed the American History Museum and the Udvar-Hazy Air and Space Museum at Dulles Airport the most.

After getting the lawn cut I spent several hours today shopping for stepper motors, a 4-axis driver and other electrical components for the Solsylva 25×25-inch CNC router I’ve been building.  I haven’t been able to work on it as much as I’d like but I have been making steady progress.  And during the first week of October I’m going to do something I haven’t done in about 10 years, which is to take a week of vacation and stay home by myself to do things that I want to do.  And my goal is to get the router finished.  But to do that I need to get my electronics and leadscrews ordered by tomorrow.  I should have done it at least 2 weeks ago.

I was going to buy my electronics from Hubbard CNC, a company I highly recommend because they have excellent prices and service.  They usually have a 4-axis kit with stepper motors, driver board,  power supply and “extras” for a good price but I didn’t see one.  So I sent them an email with my phone number and Brent Hubbard called me within a few hours.  He was willing to quickly put together a kit and get it in the mail.  That offer and our nice conversation increased my opinion of him and his company even more.

Unfortunately, Brent’s call was too late.  I’d already found and decided to splurge on a 4-axis Gecko G540 controller sold by Deepgroove1 with four 270-oz stepper motors for $601 with shipping.  Their kit is almost completely ready-to-use.  The Gecko is already installed in a nice enclosure with the power supply and the motors have cables and connectors already attached to them.  All you have to do is mount the motors on your machine, plug everything in and configure Mach3 or whatever controller software you’re using.  It’s about twice the price of a kit with a cheaper controller but there’s no soldering to do and no searching for a suitable enclosure, cables and connectors.

You can’t get much better controllers than Geckos but they are expensive.  A 4-axis G540 by itself usually goes for about $250 and 4-axis TB6560 based driver is about $86 (a 3-axis board is about $75).  If you want to try one of them then I highly recommend buying it from Hubbard CNC.  There are dozens of vendors selling them on eBay and you can probably save a few dollars buying one from someone else.  But they’re notoriously hard to set up and Brent’s drivers come tested, with documentation that makes it easy to get them running and some “extras”.  Brent told me they also sell some single axis drivers (P55052/P56056?) that work very well but I can’t tell you much more about them than that.

If you’re wondering why I need a 4-axis driver and 4 stepper motors for a 3-axis CNC router, it’s because it uses dual leadscrews for the X-axis. I’m going to connect a stepper motor to each screw instead using one stepper and timing belt and pulley system.  It won’t cost much more and it will probably take less work and be more reliable.  Mach3 makes it very simple to slave one stepper motor to another.

MachinistVideos.com

I’ve created a new web site called MachinistVideos.com that has the best videos we can find about machining, CNC, welding and metal fabrication (and model engineering and gunsmithing).  It was an impulsive act and I honestly don’t know how I found the time to do it because this has been one of the busiest summers I’ve ever experienced.  It’s pretty easy to create a web site with WordPress and that helped.  And adding new content to it is about as hard as watching TV.  I just have to look for good videos on YouTube and Vimeo and then write a short description when I find one.  It’s something I can do at the end of the day when I’m too tired to do almost anything else but go to bed (like I should).  JamesS, a contributor to MachinistBlog, has also been helping  me and my wife says she will too.  So I don’t think the new site will take too much of my time away from working on this web site or in my workshop.

Feedback & Links Please

The new site is not fancy looking because I’ve been concentrating on regularly posting new videos to it.  I would appreciate any suggestion you can give me to improve it aesthetics and especially its usability.  I’m not only trying to become a better machinist but also a better web designer.  I’ve found that I’m very good at critiquing other people’s web sites but I’m nearly blind when I look at my own.  So please don’t be afraid to speak up.

MachinistVideos.com is also almost completely invisible to the world because no one is linking to it yet.  So I would really appreciate a link from your web site if you think it’s worth one.