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Articles related to CNC Setup and Machining Techniques

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CNC Machining Tool Material and Coating Application Guide

July 21, 2017, 10:47 pm by Eldar Gerfanov

We have many helpful articles over at HSMAdvisor Help portal. But beacuse of that very reason not many website visitors actually read any of them.
It is a pitty that most advanced users will never actually visit the help section, because they already know how to operate HSMAdvisor.

And this particular one, I believe, is too useful (I just updated it to include more info) for my customers and other machinists to keep it burried in some help section that few ever read.

So here you go:

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Expanding Mandrel with Outside Support

February 27, 2016, 2:21 pm by Eldar Gerfanov

Being a CNC Machinist/Programmer is sometimes more than simply creating a program and machining the actual part, often times it is about creating efficient and accurate fixturing.

In this little project:

I had to machine rectangular cut-outs and drill holes through an already-turned steel ring. Then I had to part each ring to 4 equal pieces.

There were about 100 such rings that worked out to 400 pieces in total.

After drilling holes on an indexer I had to machine a fixture to hold my part through 2 remaining set-ups.

First half of the fixture consists of the expanding mandrel:

The work-piece would be mounted on it like so. A hole on the side is used to properly position it:

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Workholding: Soft jaws in Vise

August 24, 2015, 7:01 pm by Eldar Gerfanov

One of the most versatile ways of clamping irregular -shaped parts is with use of soft jaws.

In this one I had to machine a triangular-shaped part from two sides.

It is going to be some sort of a part holding jaw for a robot.

So step one: Machine one side of the part in vise. hold on to 1/8" of stock. So make sure to cut your part on a bandsaw oversize.

Step Two: Bolt soft jaws to your vise and machine a pocket using outside contour of your part.

Be sure to relieve corners.

Step three: Clamp your part in the soft jaws and machine the second side of your part.

One important thing to consider is: this method is not very accurate. depending on the size and a shape of your part you may be able to hold it within 0.001" though.

See attached photos of the steps below.


1. Machine one side 14402581166020.jpg 2. Machine pocket in soft jaws 14402581369241.jpg 3. Clamp the part 14402581523902.jpg 4. Machine the second side 14402581647543.jpg

Expandable mandrel fixturing

August 19, 2015, 12:55 am by Eldar Gerfanov

Recently I had to machine a few pieces after turning.

Because the very top of the part was supposed to be machined off, I could not clamp through the central hole like I often do.

Decided to quickly turn an expandable washer out of aluminum and a plastic spacer that would collapse a little bit under clamping pressure and allow the part to sit firmly against the base of the fixture.

I liked this method so much I am going to do the same next time I have similar part to make.

See pics below.

Later on i will try to post some more pictures of other setups I did.


All the pieces apart 14399592931550.jpg Fixture, spacer, expandable washer, FH screw 14399593065781.jpg Workpiece mounted on 14399593164262.jpg

Fancy Skin Work in Vise

October 29, 2014, 9:41 pm by Eldar Gerfanov

 

There is more than one way to skin a cat!

Previously i have showed how to machine multiple pieces out of a flat plate holding only on to 0.010" thick material on the outside of the part. (here)

But there is more than one way to do it.

Sometimes your part is so hard to hold, that using tabs or skin is the best, or even the only way of machining something.

Very often, working in prototyping, I have to make only one single part and designing and producing special fixturing is also not feasible.

Here is how you can easily machine a difficult-to-hold part from both sides without using a separate fixture:

Setup: Put or part in vise. Make sure to square off at least two sides contacting the jaws for accurate positioning and minimum distortion.

Program part normally. Perform as many operations on the first side as possible.

When machining outside profile, machine to the exact depth of your part.

Here is how your part might look after completing the first OP:Read More 


An old trick to reduce or prevent chatter in extension holders

August 23, 2013, 12:36 pm by Eldar Gerfanov

Shrink fit holders and extensions often come with a big through hole.

Its primary use is to allow the shank be knoked out from he back should the tool ever snap off. It is also used to supply coolant for CTS machines.

Unfortunately said hole affects rigidity of the holder making it more likely to chatter leaving bad surface finish and badly affecting tool life.

There is however an old trick to prevent or minimize the chatter.

All you have to do is pack that hole with some thick grease.

Don't forget to cap off the oppening so that grease does not escape when the tool is spinning.

Here are several photos of surface finish before and after grease application. All cutting parameters were exactly the same in both cases.


before. deep chatter marks 13772750243945.jpg after. surface finish is ideal 13772750375326.jpg tool in extension holder 13772748879991.jpg showing capped hole 13772749147372.jpg

Digging for Gold

March 28, 2013, 9:42 pm by Eldar Gerfanov

I recently had to machine an aluminum mold cavity.

7 inches deep. With 5 degree wall draft and a 60 thou radius going all the way down. Roughing was not an issue, but for semi-finishing and finishing i had to manufacture these two extension holders.

Both tools have runout of less than 0.001

The one for bigger 3/8 tapered ballnose cutter is shrink fit- i mounted it using torch.

The smaller tool is a 3/32 tapered ballnose cutter from Harvey Tool.
I could not bore to correct size, and had to ream right on.
The tool is mounted with a set-screw from both sides to prevent deflection caused by unequal clamping pressure.


13640634846051.jpg 13640634846051.jpg

Shop made CNC lathe bar feeder/puller

March 12, 2013, 8:47 am by Eldar Gerfanov

 

An attachment like this is sure to save you some time and money running your lathe unattended

And here is a sketch that i used to make it


drawing 136309494441101697049931.jpg Side view 136310728559201697049931.jpg Front view 13631072952201-631193174.jpg

One more way to Resharpen a chewed up endmill

March 10, 2013, 10:02 pm by Eldar Gerfanov

Some time ago an unknown colleague had borrowed an end mill from me.

Have i had been there i would have stressed that it was aluminum specific cutter and that it should not be used on steel.
Unfortunately i was not and it did not occur to him to ask somebody who would have known better.

Next time i look into my drawer i see this.(first picture)

Now we have a tool and cutter grinder to sharpen the OD of an end mill, but chips were so big, i would have to grind off maybe 20 thou of the diameter on order to get rid of them.

Our TC grinder does not allow to re-flute end mills, so i had to do it holding end mill in my hands.

First i picked up correct angle, and then i slide end mill upwards, turning it at the same rate as to follow flutes.

It came out better than i thought.
I was not planing to use it for finishing anyway.

And it lost only 5 thou in diameter after this hack-regrinding.


Before 13628531447330.jpg during 13628543442911.jpg after 13628543295750.jpg

Shop-Made Toe Push Clamps

January 25, 2013, 1:34 am by Eldar Gerfanov

Anybody could use a pair (or more) of push clamps around their shop.

Those handy devices convert your machine' table into a huge vise.
They are pretty mush irreplaceable when machining plates and other oversized parts that no ordinary vise will fit.

Several vendors offer their clamps. But many of them tend to be pricey. And those that are not, lack in quality.

And to be honest with you, it does not look like they are worth the amount of money their seller is trying to get from you.

In the mean time their design is simple enough to fabricate in any shop.

Here is a picture of two of four clamps i made for myself on manual mill withing 2 hours- sure beats buying mitee-bitees for 175$ a pop!!!

Made out of 5/8" thick D2 plate

1" long Shoulder in the front is tapped to 3/8-16 NC.

Slot for 1/2-13 bolt is sloped towards the back to prevent clamp from sliding under clamping pressure.

A thick 1/4" washer is used to protect T-slot from damage by the socket head.

I ll try to get more pictures tomorrow.


IMAG0540.jpg IMAG0540.jpg Drawing ROckerCLamp.png
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