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Browsing articles from "May, 2010"

Making a Lathe Compound from Scratch

May 30, 2010   //   by Bob Warfield   //   Blog, CNC Projects, Manual, Techniques  //  No Comments

This was an enjoyable video I came across:
I might follow a similar approach to make a gang slide for my Lathemaster 9×30.…

Is Carbide Always Faster?

May 25, 2010   //   by Bob Warfield   //   Beginner, Blog  //  2 Comments

I have had several people ask why the chiploads for HSS are higher than Carbide all other things being equal in G-Wizard. After all, isn’t Carbide always faster?
Well not always. Carbide is much stiffer than HSS, and this can be helpful to reduce chatter or with longer reaches. This is why we can use longer boring bars and endmills if they’re solid carbide. However, if vibration is not a problem, this stiffness is offset by Carbide being more brittle than HSS. For that reason, it can’t take as big a chipload without chipping, all other things being equal.
This is more than made up for in many situation’s by Carbides ability to run at much higher surface speeds. Even with a lower chipload, we can run higher feedrates, provided we can maintain the spindle speeds needed for those feedrates.
I thought it would be interesting to compile the trade off data from G-Wizard into a chart so you can see graphically where each one excels:

Regions where HSS vs Carbide has a better material removal rate due to a higher feedrate…
As you can see, if your spindle is only capable of running at 4000 rpm or less, HSS…

Limit/Home Switch Noise

May 23, 2010   //   by Bob Warfield   //   Blog, Techniques  //  1 Comment

I recently got my Home Switches going and decided to go ahead and enable them to act as limit switches too. That’s when I became aware of just how much noise there was on the lines. I was getting a gratuitous limit fault from noise about every 2 to 3 minutes. No worries, I did what I should have done to start and grounded the foil inside my cables to the CNC electronics cabinet via their connector. The noise went away immediately and life has been good since.
If you didn’t think you had much noise in your system, maybe its because you didn’t have a way to check? Ground the cables at the electronics cabinet end (not the machine end, that can create ground loops).…

Mach3 Users: Make all of your Accelerations the Same on your Axes!

May 23, 2010   //   by Bob Warfield   //   Blog, Software  //  No Comments

I discovered this was a problem while making my tapping arms. Due to the high rate of feed (50 IPM) and some abrupt changes of direction to follow the profile, I hadn’t really encountered the problem before. I had heard on one individual having an issue with wildly different motor tuning on a knee versus his X and Y axis. It had been said this was a bug in Mach.
In any event, as I discovered early in my machining of the axis arms, it isn’t a good idea to have different accelerations on two axes. I wouldn’t have noticed it had it not been for easing back the accel on the X axis because it was faulting too much when I run with two 6″ vises on the table. I lowered the X axis accel to match the Z and forgot about it. This latest job making a tapping arm reminded me in short order that something needed tending to.
It seems odd to me that Mach3 doesn’t account for this, and it ought to be classified as a bug. Mach’s trajectory planner should be able to properly choreograph a coordinated move across n-axes with a different acceleration and…

50 IPM Passes on the Tapping Arm

May 22, 2010   //   by Bob Warfield   //   Blog, CNC Projects  //  No Comments

I got some work done on the tapping arm project yesterday afternoon. I made the two swing blocks that are the uprights in the parallelogram linkage. Here is what the overall arm will be:

The swing blocks are the red parts…
While making the swing blocks, I wanted to play with some faster milling feeds that use radial chip thinning. Being able to do the speeds and feeds calculations to maximize performance is one of the reasons I started writing G-Wizard. I’ve got some limitations given that my mill only has a 1600 rpm top spindle speed–pretty darned slow for aluminum. That was going to seriously limit the top end of what I could accomplish.
To pick up the speed while profiling the swing blocks, I did a couple of things. First, I used a 1/2″ corncob rougher which can sail through the work a little faster. Second, I used a HSS 4 flute. I need more spindle speed to make a carbide endmill fly, but I’ve got decent juice for high speed steel. Running 4 flutes instead of 2 is like doubling your rpm, so in effect, I can go as if I had a 2 flute in a…

Gang Tool a Turret

May 18, 2010   //   by Bob Warfield   //   Blog, Techniques  //  1 Comment

Clever idea to get an extra ID tool in a turret (there’s never enough slots):

Think of it as a gang tool slide on your turret……

Way to Get Social, Okuma and Sandvik!

May 18, 2010   //   by Bob Warfield   //   Blog, Business  //  No Comments

I just came across the Okuma Winner’s Blog, thanks to a thread on PM by the winner.
What’s going on here? Just some clever tried and true marketing tactics well applied to the Social Web.
Seems that Okuma gave away one of their machines for 2 years to a deserving (in their opinion) shop based on a contest to describe what they would do with such a machine. Very cool. Contests are a good way to get interested prospects to participate and build your mailing lists.
But then they took a cool next step–they gave the winner a blog and asked him to write about his experiences with the machine. That’s pretty cool. They say your customers are your best salespeople. Well Okuma is just putting forward this “customer” front and center to tell his story. I’ll bet one of the things they were looking for as they reviewed the contest entries was evidence that each contestant could tell a good story. The submission was in the form of a YouTube video telling the story, and the winner has a great “Black Hole” story about needing to replace an old machine. Not only does Okuma get that voice talking about…

The Swing-Away Tailstock

May 17, 2010   //   by Bob Warfield   //   Blog, Products, Techniques  //  No Comments

A fourth axis can lead to tight quarters inside a mill enclosure. Enter the swing-away tailstock. Nikken tailstocks for fourth axis work have a swing way feature:

The tailstock up and ready for action…

And here it is down and out of the way so the part can be loaded…
Thanks to Boris on the PM board for pointing this out!…

What Are the Best Toolholders?

May 17, 2010   //   by Bob Warfield   //   Blog, Techniques  //  1 Comment

According to Google Analytics, one of the most popular pages on this site is the one about surface finish for milling. As a result, I am busy updating the page to include a bunch of newer information I’ve come across since I first wrote it.
For example, as part of the research, I recently read a fascinating analysis of toolholder efficacy in a graduate thesis out of the University of British Colombia (“Mechanics and Dynamics of the Toolholder Spindle Interface”) that raised some good data I hadn’t seen before:
– HSK toolholders are as much as 4x stiffer than equivalent sized CAT40 holders. This is mainly due to the dual-face contact of the HSK design.
More interesting was the comparison of the performance of milling chucks, shrink fit, hydraulic chucks,and collet chucks. The most important characteristic for finishing operations is modal stiffness. In order of best to worst performance, here is how the different toolholders ranked:

Tool Holder Type

Modal Stiffness

Dyamic Stiffness

Shrink-fit

0.89

0.065

Collet Chuck

0.75

0.155

Hydraulic

0.53

0.196

Milling Chuck

0.52

0.184

Surprising that the lowly collet chuck performed nearly as well as finicky shrink fit tooling and quite a bit better than more expensive…

Rolling Into a Cut

May 15, 2010   //   by Bob Warfield   //   Blog, Software, Techniques  //  No Comments

Here’s a great tip, courtesy of Sandvik, with a hat tip to Don “Milacron” at the PM Boards. This Sandvik video explains the gist of it:
I’m fascinated by these geometric effects. Chip thinning is another. Isn’t it interesting how Mother Nature tends to like circles better than straight lines? Chip thinning, rolling into a cut, and the trochoidal paths of high speed maching are all about the behavior of circles as we try to use them (in the form of rotating cutters) to cut the straight lines that we humans are more comfortable with. Circles are more gentle and natural in these applications. Here is another look at the geometry:

Not the chip shape to the right of the feed line (the red line is the path the cutter follows): thin chips on exit are better!
To execute an entry like this means starting the cutter out one radius to the right of the original starting location and then rolling it in along a path that is an arc with the same radius as the cutter. The folks on PM report that this works as well for endmills as it does for the face mills Sandvik shows in their…

I almost forgot: Shop Air!

May 11, 2010   //   by Bob Warfield   //   Blog, CNC Projects  //  No Comments

Somehow or other, I forgot to mention that I got a new compressor and shop air plumbing into operation last month. I now have a nice quiet Eaton 5HP 2 stage compressor installed in a room completely separate from my shop:

Way better and quieter than the Craftsman I had been putting up with, and tons more air to boot! The system is plumbed in black pipe and there are outlets all over the shop. When I need air, I just flick a switch:

For those who are curious about more detail, there is a full write up on the Shop Air page.…

Next Project: Tapping Arm

May 11, 2010   //   by Bob Warfield   //   Blog, CNC Projects  //  No Comments

Having finished my home switch project for the CNC mill, I started thinking about what my next project ought to be. I wanted something simple but very useful that would combine a little CNC with a little welding and fabrication. A tapping arm is perfect for that task as I was reminded when reading a recent thread of Hoss’s over on the CNCZone. In case you’ve never seen a tapping arm, they work like this:

I’ve had one in the planning stages for a while, to the extent that I have a page devoted to it. It should look something like this when I finish:…

Next Project: Tapping Arm

May 10, 2010   //   by Bob Warfield   //   Blog, CNC Projects  //  No Comments

Having finished my home switch project for the CNC mill, I started thinking about what my next project ought to be. I wanted something simple but very useful that would combine a little CNC with a little welding and fabrication. A tapping arm is perfect for that task as I was reminded when reading a recent thread of Hoss’s over on the CNCZone. In case you’ve never seen a tapping arm, they work like this:

I’ve had one in the planning stages for a while, to the extent that I have a page devoted to it. It should look something like this when I finish:…

Great Small Business Book: The Referral Engine

May 10, 2010   //   by Bob Warfield   //   Blog, Business  //  No Comments

I loved John Jantsch’s book, “The Referral Engine“.  Like the book jacket says, it’s about teaching your business to market itself.
It’s funny, but I expected the book to be about something else from the title.  I guess I had visions of multi-level marketing when I heard the word “referral”.   While the strategies and tactics the book espouses would be very effective for MLM, they will also be effective with any business.  In fact, a great many very successful businesses are doing just exactly what Jantsch proposes.   What’s really different here?
There is a growing consensus (finally), that the Old School marketing approach of simply browbeating customers into buying is no longer working very well.  Send them enough spam, make them watch enough Super Bowl ads,  control the shelf space at the super market so they have fewer choices, and they will buy.  Businesses with this mindset (and it is still the prevailing view) think that their biggest problem is figuring out how to extend the consumer enough credit to buy even more.  But as I said, it’s not working.  Newer generations are growing up savvy to it and older generations are tired of it.  The Internet above all has…

Shopmade Jet Engines

May 7, 2010   //   by Bob Warfield   //   Blog, CNC Projects, Cool  //  No Comments

Someday I want to try my hand at making a little gas turbine (jet engine). In many ways, these are some of the most demanding machining applications you will find. They are similar to machine spindles (another demanding application) in the sense that they are rotating and require precise and durable bearings, but they are harder in the sense that they spin very very fast and involve a lot of heat as well.
There are shortcuts available, however. Rather than build a turbine from scratch, one can adapt a turbocharger from a car or truck to the application. The high heat/high rpm rotating assembly is then already taken care of. Still not an easy project, but much more doable. If nothing else, these monsters are impressive to watch. Here are a couple videos for your entertainment:

Is it just me, or do these things look like they’re ready to explode at any moment?
 
You don’t have to be Jay Leno to have a jet propelled motorcycle!

Bunch of Bubbas in a Garage with Beer and an Old Turbo: Git ‘er done!
(Love the red hot tailpipe and the oil so hot it is smoking: Guys says not enough fuel?!??)

Scratch…

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