2017 POTD Thread Archive

[roadie33]

savarin,
What are the knobs for ?

 

[savarin]

Some sort of electronics equipment for a friend. The old plastic ones disintegrated.
I think its for either a frequency analyzer or oscilloscope.
They fit a 4mm shaft.

 

[john.oliver35]

And I'm just now trying to figure out sketchup. I too am old school pencil and paper, having a hard time with this but I know I have to stick to it and keep playing with it till I figure it out.

I used sketchup for a while, but found it frustrating as a design evolved. Sketchup doesn't seem to track feature parametrics - everything is turned into a series of lines and these lines become the design primatives. This can be really frustrating for circular objects - the circles turn into a number of line segments. when you later need to intersect that arc, the intersection is with one of those little lines, not an actual arc. Some subtle dimensions then get messed up.

I have been using Fusion 360 lately and it seems a lot nicer. Works a lot like SolidWorks, but more intuitive. It is truly parametric, meaning that when you draw an arc for instance, the data for that arc segment (i.e. center position, radius, start angle, stop angle) remain within the part definition. Then you can change it later based on these fundamental characteristics, rather than the arc having been reduced to a series of line primitives.

That said, I often just start cutting and make it up as I go

 

[woodtickgreg]

The main reason that I am trying to learn sketchup is for wood working and cabinets etc. I think for machining stuff something different would be in order.

 

[wawoodman]

Sketchup is a fun thing to play with. I've done a couple of projects with it, but when I need a quicky for a prospect, I go 2-D with RealCADD.

Sketchup has a neat iPad app (for display, not drawing) that lets you pan around the job, and look at it from any angle, zoom in or out, etc. Clients are generally awed!

 

[JimDawson]

My little project for the day. A customer needed some rework on 13 aluminum frames due to a design change. The inner flange needed to be machined to 0.175 wide from the original 0.090 wide. So how do you hang onto a 1/4 thick aluminum trapezoid and machine the flange? It's pretty hard to measure a trapezoid accurately, especially one where the angles are not the same on each side, about 2° difference.

The good news is that I have a spindle microscope/camera system for the mill, accurate to about 0.0005. First I drilled a couple of dowel pin holes in the spoil board the align the piece on the X axis. My software has a point cloud function that saves the points as a G-code tool path, this can also be used to ''teach'' the machine for facing and hole layouts, same as a MDI (manual data input). So all I have to do is pick any point on an edge and set 0,0, and click the mouse to save the position. Then over to another point, click, move, click, rinse repeat until you have enough points to define the shape. Once I have the data points I save the file, and open the NC file in CamBam. Then click on Toolpath to Geometry and then export as a dxf file. Then open the dxf file in AutoCAD and connect the dots. All of that probably took less time than typing the description of it, and all done on the machine computer.



So now I have an accurate drawing of the part, and created the toolpaths in CamBam, so the next step is to mill a 0.125 deep pocket in the spoil board to fit the parts. The good news is that these parts were waterjet cut so are all about the same, some variation but close enough. Note the finger hole at the bottom of the pocket, this allows you to get under the part to lift it out.

One kind of strange anomaly with these pictures, the part is about 1.5 inches narrower at the top than the bottom, but the pictures show it as being almost a square. Must be the perspective.



0.139 2 flute endmill, 0.075 DOC, 50% stepover, 3100 RPM, 10 IPM, about 0.0015 chipload. 7.37 minutes per piece + about a minute to load/unload. Kerosene coolant, flow rate about 1/2 cup/hour, it's flowing in the picture, but you can't see it. You have to put your finger in front of the nozzle to see if it's flowing (no, not with the spindle running ), it doesn't take much to do the job.

Held in place with just 4 screws & washers centered on each side. Just screwed into the 3/4 thick MDF spoil board.



Now I can go buy some more toys, 'er tools. It's the little jobs like this that support my tool habit.
.
.

 

[Martin W]

Jim , I get 2 sheets of MDF on every order of sheet goods. I call them protection boards because they protect the sheets I am getting. They are usually faced with some funky colour and one side is usually messed up, but we use them for bench tops, jigs, patterns, sacrificial router jigs and dozens of other things. Some times you can't find anything wrong except a maybe a lift truck smashed one edge. They all end up in the dumpster eventually but at least they get a second use first.
Cheers
Martin

 

[woodtickgreg]

I agree, will work for tools!

 

[Hukshawn]

Made a whackin wrench for the mill. Came together fairly well. Brass on one end, mild steel in the middle, and welded on a cheap 17mm socket on the other end. Handle was turned from a galvanized ground rod I had from a outdoor kitchen I wired last year (all aluminum and steel, lightning magnet and had an induction charge going through the aluminum, had to ground it out).

No idea what the metal is, it turned kinda strange. The chips coming off the carbide were not something I've encountered before. Came off kind of like those little firecracker things you can buy. Little black slug that just grows into a black worm type thing. Sort of like that.
The gnarl is light, I didn't want a full formed gnarl. This is soft and nice feeling while still giving grip.

Oh, and I bought a surface plate. 18x12x4. B grade from busy bee. Super happy about that. $55. Can't go wrong.

 

[HBilly1022]

I made a couple of dovetail insert holders. The first one was cut on the wrong side . Would have been fine if my mill drill had a reverse but it doesn't so I made a second one. I tried it out but the insert kept chipping plus it hammered pretty good so I gave up on it and ordered a couple of HSS 60 deg cutters from overseas. I want this so I can make the tool rest in Harold Halls book.

I was thinking afterwards that the chipping could have been caused by flexing in the tool holder. I used some 3/4" bolts for the steel and they weren't grade 5. Don't know what they were because they were stamped with numbers I haven't seen before. They also seemed soft when machined. Maybe the inserts I used too. Don't know what they were either since they came with a set of cheap tools I got.


Also made this thing. I had to have one after someone else on this forum posted pics of one he made. Now I just need to get some decent wire for it. Mechanics wire doesn't seem to be strong enough.



And finally, a project of many days. Man I'm slow at machining stuff.


I still need to adjust the angle of the pin but I couldn't wait to try it out.




Here's a pic of a test run on a piece of scrap. 40 divisions, 4 short, then a medium, 4 more short, then a long. All done without me having to count or keep track of what mark was done last. This thing works pretty slick. I got the plans from one of Harold Hall's books. I had to alter some of the dimensions because his plans were for a Myford 7 and my lathe is bigger. There are quite a few little pieces to this thing.


Edit: here is a link to Harold Halls site for the engraving tool. There is video too if anyone is interested. http://homews.co.uk/page315.html