Wednesday, April 13, 2016

Onshape + Kiri:Moto does 2.5 axis toolpath gen in one interface

https://www.onshape.com/cad-blog/partner-spotlight-kirimoto

At first I was like 2.5 axis? What good is half an axis? Then I realized this was related to 3D printing and laser cutting. AH, that makes sense. In this context, the half an axis control is the 3D printer's waterline. The waterline only increments once per layer of print, and it increments by the thickness of the deposition layer.

This is a nice tool to add to Onshape for prototyping. There are other CAM plugins for generating gcode from Onshape models, but they are pretty much export tools to move models into desktop software. So Kiri:Moto is pretty cool because the toolpaths are generated right in Onshape.
Besides CAM, the other thing I'd like to do with Onshape models is FEA (finite element analysis).
Good 3D CAD can get pricey. Good desktop FEA software is expensive, and for a good reason. It's expensive to develop! These are not simple problems to solve. They took decades of research and refinement to get where they are now. At the time of this writing, it is still not possible to automatically generate optimal 5-axis tool paths. It's a complex problem!
If you're a small shop or one man operation without the big $$ to purchase a $10k software license for a desktop machine, there are some newer options that are going to become very popular. Cloud based services can sell you compute time by the hour.
Fidesys has a new simulation plugin for Onshape that looks like it would suit the needs of a small shop well:
https://appstore.onshape.com/apps/Simulation/VYJMBUJCXRXFDJV4U4SOMXLHDF5CIJKCVKVB3YY=/description

Thursday, April 7, 2016

One side of a 4-link assembly. Looking for interferences etc. It uses standard grade 8  9/16"x4" bolts and lock nuts,  1" and 1.75" .120 wall tube, sleeves and poly bushings. It can be adjusted (after welding up properly) for pinion angle at different levels of squat. The shock mounts are adjustable for any laterally bolted shock or coil-over set. It has 10" of adjustment for the shock mount position.
 I'm going to try a version with high misalignment rod ends instead of 2 5/8" bushings. I've seen a lot of kits with rod ends, but they're much narrower. This is only the 4 link, no other locating bars included. This design requires a Panhard bar to locate the rear end side to side.

Tuesday, April 5, 2016

Ford 9" 4 link brackets for jet/plasma cutting. Looking for someone to make four of each bracket.

Thursday, March 17, 2016


Rolling mill design changes. The previous mill frame was huge and difficult to make without making some big iron castings. I don't know anyone who can make a high quality ductile or nodular iron casting in the hundreds of pounds for a one off part without it being way too expensive. The critical/stressed members of the frame do not need to be integrated directly into the parts that keep the frame from falling over. The above frame ^^^ is machined from 2x3x8" 1018CR or hot roll bar stock. with alloy/chrome wear proof steel guide rods also running in bronze bushings. All bores are press fit. There are no standard sized pillow block bearings in this design, just 1 1/4" ID bronze bushings or some heavy duty roller or maybe double taper bearings. I'd like to load this into solidworks for FEA to see if my dimensions are sane. This model is built in OnShape, which is a cloud based CAD SAAS. It would be really really cool if they did FEA.

Friday, February 5, 2016

Lodge & Shipley Model A 14" Lathe specs

I've been hunting down brochures and manuals for the L&S Model A lathes.  Here are some numbers:

L&S Model A 14 Engine lathe:
Swing over bed and carriage wings: 16 1/2"
Swing over cross slide: 10 1/2"
Center distance: 30"
Key drive spindle nose size: No. 1
Spindle through clearance: 1 3/4"
Morse taper of centers: No. 4
Spindle speeds: 12
Spindle speed range: 18-540 RPM
Threads and feed changes: 55
Motor horsepower: 7 1/2
Machine net weight: 5400 lbs. (I was guessing 3500# but it's a lot heavier)

It can swing 16.5 inches over the ways, which is more capacity than I figured on.


Thursday, January 28, 2016

Lodge and Shipley lathe

I bid on this lathe not expecting to win it, but hey, be careful what you bid on, you just might get it!

So Raphael from the rigging company that listed it was nice enough to send two of his guys over with a forklift to unload it. 

More pics over on instagram:
A photo posted by Brian Madigan (@brian.madigan) on




The lathe doesn't have the most huge swing, (classified as 14"), and no gap in the bed, but it has a lot of other things I like. The motor is 240v 3 phase and located underneath the headstock casting behind those nice louvered iron doors, driving the main shaft via a gang of v-belts. I haven't run the motor, but going through the gears and rotating the spindle I don't feel any big crunchies. I don't know the year this one was made, but most of them were made during or just after WW2, and they're extremely well made. So unless it was abused horribly it should be working nicely within a reasonable envelope of wear. We'll see if there are any missing teeth in that gearbox...
The whole thing is really, really greasy on the outside and the grease is full of aluminum oxide abrasive. I can't think of a worse combination of things to be on a lathe! I found a 14" aluminum oxide PSA backed disc sitting by the faceplate. It was stuck onto the faceplate at some point like a big disc grinder. Whoever used this lathe as a big disc grinder didn't bother to cover the ways to keep the dust off. So once I move it inside it's going to need a thorough tear down, degrease and cleaning. I'll be taking pictures of all that as I go, from making some machinery skates to getting it back up and running. Just moving this thing becomes a big project!
I'll keep the Instagram pics coming as this one progresses.

Tuesday, January 26, 2016

Using Onshape to create a proper drawing for this rolling mill. I have not drawn a few parts like the guides, sprocket teeth, roller chain, motor etc. 


Wednesday, August 19, 2015

The three most beautiful British sports cars within reach of the enthusiast with a limited budget

50's Triumph TR3A: Swooping fenders, low slung, reasonable power and handling with 1930's technology.


MG MGA: The 56 to 62 MGA is a classic looking car, with swooping fenders and a long hood ('bonnet' if you prefer). High export percentages mean that they're not very rare in the US.


Austin-Healey 100/4. Another beauty. The Austin 3000 is more sought after I think, and the prices of those in good condition reflect that ($80+k in the US)
The 100/4 is not as powerful or smooth as the 3000, but it is very good looking. They can be had in running condition for less than $20k.



All of these were available in other forms: convertible roadsters and removable and fixed hard top roadsters and coupes. There were also fiberglass creations made to fit on these car's frames.
So if you are a fan of open tops, tall skinny tires on wire wheels, manual everything, light weight and good power to weight ratio for the time, these are the perfect British cars with pedigree and class for the same money as a typical American muscle car. These are the pre-pre prototypes for the AC Cobra and other big engined roadsters. They have a more refined, classic look though, without the giant fender flares and the necessity for huge rubber to handle the V8s.

Tuesday, July 28, 2015

Apache Cassandra

I'm writing a post about Cassandra for Orbitz's tech blog. I just thought I'd leave this here because it may not be appropriate there...

That is all.

Wednesday, March 18, 2015

Find steel locally

I've built equipment mostly from local steel. Stuff I can't find locally is from onlinemetals.com. They are good at small orders. However, for bigger things that weigh over a hundred pounds, local is better. Also some of these might just have big drops they can't find a use for.
SB Specialty Metals Cincinnati Tool Steel co Key Metals

Update: Metal Supermarkets has distributors all over. There's one 5 miles from my house, and I can order anything and have Zero Shipping Costs, as long as I pick it up myself.

Cutting ISO threads (by trial and error, mostly error)


 I recently got a 8" Bison 6-jaw Set Tru scroll chuck for about $100. These are forged steel, made in Poland, and are generally around $2000 for a new one. I figured this one would be worn out, since there are more moving parts in a scroll chuck than an independent jaw chuck. The internal ring gear is pretty well sealed, so it doesn't usually wear out if kept greased, but the centrifugal forces of the spinning chuck sling the grease out and pack it into places where no mechanical engagement happens, and over time the grease hardens and doesn't do much good. The ring gear can wear if the grease isn't replaced, from contamination or just from age. There's not much wear on this ring gear or the turning gears at all. They still have the original machining marks, just a little polishing on top of that.

The Bison scroll chuck (taken apart for cleaning and lube). I didn't show the Set Tru screws :( or the shoulder where the chuck registers. So this is just the chuck, in pieces.




The 8" backing plate blank. Cut from 1 1/8" 1018 round, ~2" length.

Boring/threading 1 3/4 x 8 TPI thread. Shop made boring bar from a 1" 1018 bar with HSS bit ground to 60°. You can just see a few threads about 1" in from the face. The back plate is drilled from the back and bolted to a slotted face plate that's trued to the spindle. 

I don't have ANY kind of thread gauge, or a snap gauge, or any way to measure bores deeper than 1/2". I'm cutting this to 1.80 on the outer bore. An ISO thread should have all of the dimensions below included:


So one way to cut threads (single pointing) is to grind the tool to ~60°, and set the compound angle 29.5°, which is .5 less than half. A hair less than half is basically the idea here, because when you move the tool into the thread by a few thousandths per cut, only the leading edge of the tool has to cut, and the trailing edge is not 'dragging' because of the added clearance angle.  The dragging side of the tool would create heat and ruin the tool and maybe the part. Plus, the tool will try to get ahead of the lead screw (where there is backlash), and tend to make the pitch longer as the thread advances.  

 This is how threading is taught in schools, where the lathe is an old South Bend 9" with a not very stiff lantern tool post. If you plunge cut both sides of a thread in that setup, straight in with no compound angle, you'll get a lot of howling from the tool, broken tools and not very good threads. Especially if you're threading from the end of a boring bar.

Another way to single point a thread is to use a half tool without the back cutting edge and feeding with the compound at 30ยบ.  Any flex in the tool or cross slide will probably make the left face of the thread rough, but the 1/2 degree is taken out of the equation. This thread would require more cleanup.

Regardless of how the tool is ground, there's the question of how much the total compound feed needs to be to complete the thread. The rule of thumb equation is .708/threads per inch. So in this instance .708/8tpi = 0.0885". So your compound needs to feed forward from zero to 0.0885 in increments of a few thousandths per cut. That's one method.

The no calculation involved method, is called the zero-to-zero method.
Touch the tool to the major diameter, set the compound and cross slide to zero. Back out the cross feed enough to clear the part, move the cross slide out free of the part, reset cross slide to zero, and advance the compound until the desired depth of cut is measured. A dial test indicator on the compound touching the major diameter will measure the desired depth. Reset the compound's dial to zero.
Starting your cut from the major dia., advance until the compound reaches zero.

At the end of either method, a really light spring cut is taken using the cross slide feeding into the cut straight to clean up both sides of any marks from wobbly gibs or tool flex. A file is run over the tops of the threads to remove any burs.

I didn't mention anything about change gears, gear box or threading operations besides the angles involved here. Gearing is specific to the lathe, and threading operation is best shown by demonstration.

Friday, February 14, 2014

Blanking and grinding

A few blades blanked and rough ground. 1095 and O1 steel. 

Trailing point double edge
"Inara"
Straight tanto point

Thursday, May 16, 2013

Package structure


Package structure is not something to be considered idly.
The first thing I do when I look at an application is
$ tree -d src/
And I get something like this:

com
 --host
 |-- core
 |   |-- dao
 |   |-- domain
 |   `-- engine
 |-- service
 |   |-- business
 |   |-- adapter
 |   |-- exception

What do I know about this application from its package structure? Not much. It has a core, an engine, that's exciting. But not at all descriptive of what it does. Sounds like a spaceship! or an alien weapon!

However, if I were building a spaceship, I'd do something like this:

org
--ship
|-- lifesupport
|  |-- atmosphere
|  |-- gravity
|  |-- replicator
|-- communications
|-- propulsion
|  |-- thruster
|  |-- impulse
|  |-- warp
|-- defense
|  |-- shield
|-- weapons
|  |-- phaser
|  |-- torpedo

OK, so a space ship is much much easier to design than a piece of software! I have all the major features described at the top level. I can tell what the ship does, what its major components are.
The ship's design is organized by Features of the ship. Not by layer or any other attribute. For example, a builder or a command isn't a feature of a piece of software. Neither is an exception, a dao, a domain, an adapter..
These are all layers or programmatic idioms. Grouping classes by layer or type is a common mistake in designing software. It is always taught that one should design by feature, not by implementation detail.

Monday, November 12, 2012

Custom stamping dies

Henry Aevers Co. "EverStamp" Ebay store "If it's worth making, it's worth marking"

Power Hammer notes

Dupont linkage: The total stroke of a Dupont toggle machine is 2x the crank offset, plus the distance between dies and the upward stroke while compressing the spring.
Dupont patent:

little giant

Little Giant sells springs, toggle links, etc for the 25,50,100# hammers. Instead of trying to calculate which truck spring to buy, just get a complete toggle link from them. Use the same crank offset as the LG. Or use the LG crank. I like the later LG upside-down Pitman arm. Buying the above from LG is probably less expensive than making it all. And it would be correct the first time. No need to re-invent the whole thing. Most of the early tire hammers used big structural tube as the frame, in place of the big sand-cast iron frames of the early 1900s power hammers. Instead of structural tube or I-beam, use an A-frame like the Japanese power hammers. An A-frame hammer with a separate anvil can be deconstructed and moved more easily than a monolithic design. An a-frame can be made stiffer than a structural tube or beam, which will tend to develop oscillations and rocking with a small base and high center of gravity. The recommended anvil weight ratio (from IronKiss) is 16:1. A 6x36" bar of 1018 should weigh around 289#, but I've seen different on the scales! 7x36 would be closer to 400#, the ideal weight. For a 50# hammer, a 11" base.. Metals weight calc for dimensions. http://www.machined-castings.com/calc.html

Truck/Trailer springs:
http://www.truckspring.com/trailer-parts/trailer-suspension/double-eye-trailer-springs.aspx
Meh. Bow spring or coil.

Thursday, November 8, 2012

Little Giant Hammer Co

http://www.littlegianthammer.com/

These are the owners of Little Giant company. They bought the rights and tooling a few years ago to help people restore and maintain their Little Giants. Great place to get parts even if you don't have a little giant. Almost everything but the cast frame is available. Most of the parts which were problematic have improved replacements here too.

Wednesday, October 24, 2012

Ford Bookmobile - Prison van?

Ford Bookmobile

This is an ebay auction for a strange bookmobile. It appears to have been either converted to a riot/prison van or just had some bars put in it to keep people out. Check out those bookshelves! It would make a really cool RV.