My Dad has already said he was gonna stop by this Saturday at the house. He's a 40+ year electrician, so I should at least have mine up and powered on. Then to figure out how to use it!
My Dad has already said he was gonna stop by this Saturday at the house. He's a 40+ year electrician, so I should at least have mine up and powered on. Then to figure out how to use it!
More tooling! I picked up a carbide insert facemill, a set of parallels, and a set of angled gauge blocks. Total price was right around $100 (thanks, China!)
The mission? To create a pair of wedges for my dad's Bugeye Sprite suspension.
Success! Note: I didn't drill the hole in the middle; he did that by hand after mocking everything up. I'd say these came out pretty well for a first attempt at something like this.
Next up: Let's build an axle! A buddy asked me if I could make something that would transmit power between two of these flanges 10" apart.
I ordered a dividing head, but now I'm at my first roadblock: How do I figure out what these splines are, and what I should cut to match them? Anybody have any guidance here?
1st count the number of teeth. 2nd determine the tooth shape. It looks like they are 90 deg. 3rd using 2 small dowels try to get a pitch diameter, easy if there are an even number of teeth. If the teeth are 90 deg. tip the head of the mill at 45 deg then use an end mill to cut the teeth in the shaft. Make a test piece first to refine the process. This is a very ambitious project for someone just starting out.
Well, I'm nothing if not ambitious.
Do I need to pick up something like this before I proceed?
They would help, but a couple of correct sized dowels would work. Just find a dowel that touches the sides of the teeth and not bottom out or not just sit on the top.
Use a couple drill bits that are the same size.
We started on the axle tonight, and successfully finished a prototype. Success!!
Very cool :)
Is the test piece just for fitment, or are you actually gonna use aluminum?
Cool. You might want to stone a small radius on the end mill for strength.
Jeez, Tom, you've really aged. The beard came in nicely though.
TVR Scott said:Jeez, Tom, you've really aged. The beard came in nicely though.
Apparently all of my friends are incapable of operating a camera. That's Johnny from Nine Lives Racing. He earned the very important job of operating the dividing head.
In reply to Mr_Asa :
Just a test piece for fitment; waiting on a carbide endmill to make the real thing out of 4140.
Late to the thread but very cool.
A buddy of mine, who later became Howe & Howe's shop foreman, was a trained machinist as was his father. When I met him they had a small machine shop at his dad's house with pretty much just a lathe and a band saw.
He was later tasked to get rid of the substantial amount of metal around his dad's property so started making metal runs. One run he dropped off $x amount of metal, but saw the head of a Bridgeport sticking out of a pile of metal. He was friends with the guys at the scrap yard and they helped load the complete BP onto his trailer. He ended up paying under $50 for the machine since it was offset by the amount of metal he had just dropped off. It ended up needing a motor and the table adjusted to less than a thou tolerance.
It was 3-phase and they did not have 3-phase so he got a converter. He said something about sometimes having to spin the lathe or something to get enough power for bigger jobs, but I do know understand any thing electrical over 12v so I never got the gist of what he was saying.
One of my current good friends just put a milling machine and a lathe in his shop 10 mins away. I just have to ask to use it.
I ran into a deal when a friend had to liquidate his shop, got a Gorton Master Mill, about half again the size of the Bridgeport. Got it cheap, because it has an odd ball taper making it hard to get tooling. Soon there after I picked up a 16" x 42" lathe with a ton of tooling for the price of the 1" Jacobs chuck that came with it. It's big enough to do 15" car wheels, and the drive shafts for the small sports cars I mess with. It takes a while to sink in but once you realize with a lathe and a mill you can make anything including more lathes and mills, it is very empowering and confidence building. Enjoy!
In reply to Tom Suddard :
I'm an electrician, but I have been trying to learn machining for many years. When I heard one of the machinists was retiring I would go and see if he wanted to sell any of his tools or consumables. Twice I was able to buy a shoebox full of end mills for $20.
I don't have much of an update to report (been sidetracked getting the new lathe up and running) but I did go to an auction this past weekend and picked up a few more papercuts, errr uhhh I mean "Goodies."
First up, a set of gage blocks. Not complete, but plenty good enough for now. For $40 I'm content with my purchase.
I also bought $40 worth of files, which wasn't the best deal in the world but considering I own one (seriously, one file) seemed necessary to avoid a late-night file shopping trip whenever I eventually get frustrated enough to buy more.
I also bought this tapping head for $60. I have no idea if this is a good deal or not as it's the wrong taper for my mill, but it's cool as hell and I figured I'd at least be able to put it on eBay for what I paid if I gave up on using it.
And finally something I bought on eBay, not at the physical auction. Depending on how you value my time, this was either a waste of $80 or a discounted way to be able to tram my mill quickly and accurately.
Okay, time for an update. Remember that axle project? It went great, except for one problem: I couldn't replicate it. Future attempts produced parts that were a 5-10 thousands off in one direction or the other, which just isn't close enough for something like this. I checked my setup a few times, then realized the problem: I just wasn't good enough with the dials on my Bridgeport.
Each handle has a dial graduated in thousands of an inch, and turning a handle 10 thousandths of an inch theoretically means the axis will move 10 thousandths. So why couldn't I make accurate parts? Simple: Compounding error, the machinist's only natural predator. Every time I turn a knob, it's not exactly perfect--that would be impossible. So a 0.010" move might actually be 0.011" or 0.009". This gets worse when you change directions: Every leadscrew has backlash, meaning there's slop when you change direction.
These problems are minor when doing big parts--who cares if something is 3.001 or 2.999 inches long--but when doing small parts like this axle that have an equal number of moves to a larger part, the errors stack up and it's tough to make repeatable parts. Oh, and using the dials is slow, too: Every move requires knowing where the tool is and where it needs to be, so you can add or subtract the right motion. Keeping track of where the tool is across each move requires a calcuator and scratchpaper, which takes time and offers more opportunity for error.
There are two ways to solve these problems: Become a machining savant that can spin each knob perfectly, corrrect for error and backlash in real time, and track the tool without scratchpaper. That's probably how they did this in the 1930s, but I don't have the time or patience, and perfecting my technique with knobs will never be as accruate as the other option: Install a digital readout, commonly abbreviated DRO.
DROs are awesome for one main reason: They track the position of the axis, not the handles or screws, which means rather than measuring the input and inferring the output, like those scales on each knob, they just track the output. This is more accurate, and means that measurement errors don't compound over time. Plus, they display this information on an easy to digest display, which also brings a calculator and some built-in formulas to calculate more complex geometry.
So, let's go DRO shopping. I won't dive into the difference between glass and magnetic scales and such here, so here's the Cliff's Notes version: You can buy a name-brand DRO for about $2000, or an off-brand for as little as $200. Prices vary based on the quality of the display, the quality of the instruments actually measuring each axis, the mounting hardware included, the number of axes and the post-sales support.
I ended up choosing a generic imported LCD display, and pairing it with generic glass scales. I measured my machine's X, Y, and knee (Z) travel, then specc'd glass scales to fit. All-told, this DRO system cost $391. I saved tons of money by choosing to make my own mounts for everything, going with an off-brand, and going with the more-fragile glass scale design. As little as I use this machine compared to a production shop, I didn't feel the more durable scales were worth the price increase. I'll just have to make sure I keep these away from impact and coolant. I'll admit the LCD display was a bit of a splurge, but I figured the interface would be much simpler to understand than an 8-digit LED display with mediocre instructions.
Installation took a few evenings, and mostly involved drilling and tapping lots of holes. In fact, I only needed to make one part. Overall, 10/10 and way easier than I expected:
Can you elaborate on "glass scales" versus, umm, non-glass?
In reply to Keith Tanner :
Sure, here's some stolen text from TouchDRO.com
Glass scales are a form of a quadrature incremental optical encoder. They use a strip of a high-quality glass with evenly spaced microscopic marks etched into it and a photo-electronic reading head that moves along it. The marks are commonly spaced at 5 micron distance, but 1-micron versions are commonly available as well. The head contains a photo sensor that consists of photodiodes precisely spaced at a distance that is either 75% or 125% of the distance between marks. Scale's internal circuit conditions and amplifies the detected signal; so, the resulting output consists of two square waves that are 90 degrees out of phase. The DRO is able to detect the pulses from the scales and, by comparing the state of the two channels, interprets the direction of the movement.
The other common option is a "Magnetic Scale" which uses magnets. These are less breakable, but also seem to cost 3-5x more. Glass scales work fine as long as you can keep a strip of glass glean and intact next to a machine that literally shakes the ground when it's turned on. Fingers crossed!
Ah, I probably would have called that "optical". Thanks!
1-5 micron scale!!!!!! Good lord.
Yeah, I went with the 5 micron version. There's no way anything in my garage is accurate enough for that to be a problem.
Keith Tanner said:Ah, I probably would have called that "optical". Thanks!
1-5 micron scale!!!!!! Good lord.
It's essentially the same tech as a CD player, shine a light and count the dots...
The name is literally just the material and scale as in "machinist measuring device," so metal scale, plastic scale, glass scale, etc.
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