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Messages - RICH

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911
General Mach Discussion / Re: cnc training cources?
« on: May 18, 2016, 06:44:53 PM »
I would suggest you just buy CNC PROGRAMING HANDBOOK by Peter Smid.
It covers a lot. There is also a book by Haas on programing in Members Docs.
The Smid book in the first 100 - 125 pages will ground you in basics and will be a reference for years.

Save your money for courses that give you credit or certificates.

Just my nickel,

BTW, talk to machinists  and find out what they are required to do at work, what they earn, the prospects of work in your area.
Nothing wrong with talking to shops if they would be interested in hiring you as a helper for the summer.

And remember this, a career is only as good as YOUR ability to secure your next position or job.
Fact of life is like .......... big pay the job sucks....great job the pay sucks....never a true balance anymore of things being just right!

GOOD LUCK in your pursuit of happiness,
  
RICH

 

912
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: May 17, 2016, 07:30:36 AM »
Quote
Yes but what i am saying is - is it ok to rely on soft-limits alone to stop the machine self destructing?

It all depends on the level of protection for the machine that one wants to have and the working environment that they are in.
Don't have any switches on any of my machines, but, they are rather  small and no damage will occur.

If it's for safety then you would want to be  redundant.

RICH

913
General Mach Discussion / Re: 3rd axsx on lathe
« on: May 16, 2016, 03:43:11 PM »
Randomly looked through your posts and happened to find it rather quickly.

I don't keep any records at all, but do  file some  text for on things that may be of value on a particular
subject matter.

RICH

914
General Mach Discussion / Re: 3rd axsx on lathe
« on: May 15, 2016, 04:10:56 PM »

915
General Mach Discussion / Re: Multimeter info
« on: May 15, 2016, 11:35:17 AM »
Going to expand this thread a little......

GENERAL ADVICE:
 
Unless you are going to use all the functions and desire accuracy of higher end instruments I would suggest
one don't spend a lot and be practical on intended use of what and why you buy something. There are many
different "toys" available, some worth buying new because of todays technology and associated cheap price.
I will add that a specific tool even if used once a year purchased at "steal" price could worth it's weight in
gold when your doing something. Any electronic used "toy" should be considered faulty, but, an attachment
may worth the chance. Know the instruments you are buying, be patient and you can have a lot of practical use  
"toys".


SO, that said and it's just my opinion,

Volts,Ohms,Current,continuity Multimeter................
Have a Fluke 87 & 77 and mostly use the 77. Another cheapo one is in the auto tool box. One can get a lot for
your money these days.

A dual trace scope can come in handy and you can find some used ones reasonably priced. Functionality,
bandwidth, sensitivity, etc all add to the cost. Have two of them 20 & 400 Mhz, don't use either of them
often.

Then you have temp measurement........
You can get probes which work with the higher end multimeters, but, individual
digital hand held infared or thermometers with probes are nice also. All depends on what
one is going to do with it. An infrared nonconctact with emissivity adjustment is a very usefull item.
There are manny available today resonably priced.

Then you have RPM measurement........
This is one thing that you should have. There is nothing wrong with contact speed indicators ( Biddle,
Hassler, etc ) because if you can't shut the rotating item off it may be the only way to measure rpm and they
are quite accurate. The digital tach's are just great to use and you can get one for cheap!


Then you have inductance and capacitance measurements.........
Comes in handy if you want to know some characteristics of the unknown stepper, but, the average guy
won't be interested or use one, and yes some of the higher multimeters provide these functions.

Then you have you AC amp measurements.......
A clamp on meter is usefull to measure current draw.

So there are a lot of "toys" out there and can find some real bargains if they take their time.

Here is some prices and toys and most are handheld:

RPM MEASUREMENT:
- Digital Tach DT-2234C ~ $11 on EBAY today ~ very accurate and just great for checking or setting rpm.
  I modified a contact strobe attachment from a high end but broken digital tach $3 from flea market
  so it can be used on contact.
- Biddle, Hassler or other mechanical brands - why bother when you can buy the above today

Multimeter:
- Fluke model 77 - $10 from a pawn shop ( I usualy have  a few batteries with me so i can test stuff when
  looking for stuff. )

Dual Trace Scope
- B&K 25 Mhz with probes - Flea market and could check the trace before purchase ~ $50

AC CURRENT CLAMP METER
- Sperry digital with leads/case - and also has typical multimeter function ~ $12 ( took a chance
  didn't have a battery with me to test, the leads were worth the money ) like new and works fine.

TEMP MEASUREMENT
- Whal - digital infrared nonconctact with emissivity adjustment ~ $15 Garage sale
- VMR Taceable Digital - Data logging with probe and case ~ $5 flea market special and like new!

TORQUE MEASUEMENT
- Look for In oz torque wrench, beam type is ok 0 to 28, or 1/4" drive adjustable say 20 to 100,
  but my best find  was an actual small calibrated Gauge 10-120 in oz / reversable and very accurate.
  That's what's used to find  the affect of bearing preload or gib adjustment on min axis torque and backlash.

In summary you can have a lot of use full toys for under $100.

FWIW and may your dumpster diving adventures be fruit full,
  
RICH




 

916
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: May 13, 2016, 11:05:09 PM »
Quote
2:1 or 3:1 reduction on X&Y?

Let me answer that this way as it's all a trade off with steppers.

A reduction will increase the steps per unit value so resolution goes
up,torque delivered to the screw will be increased, but the motor must
turn faster for some desired feedrate / rapid move and that can affect
motor acceleration and max velocity. So you need to look at it as a system and
find what is required to accomplish what you want.

Also note that stepper motor curves are done at voltages that may be less or more
than what your power supply may deliver. Higher voltage will increase motor speed
but remember that as speed increases the torque will drop.

That's why knowing what smeone else did with a similar machine is very helpfull.
Even if all is calculated you don't know until the machine is run what you have.
But if you did do some basic design you know things should be satisfactory.

RICH

917
Dickeybird,

Hopefully gave you some ideas for a cheap system that can be home built.
About $30 if you don't include the digital angle finder ( Harbor Freight and it's magnetic to .1 deg about $25).
 
RICH
  

918
Quote
Has anyone else had this problem with China CNC's?

Not sure what F/UP is. Care to elaborate on that?

Have you followed the instructions that came with that controller?

RICH

919
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: May 13, 2016, 07:19:34 AM »
Davek0974,

Link below just for thoughts....it's for the Z on an Atlas mill.

http://www.machsupport.com/forum/index.php/topic,7396.msg127816.html#msg127816

One pic shows the Z driven by using a small stepper ( 80 in oz) using the Z fine feed.
That was no good / don't do as you end up with backlash. Similar to what Hood posted is a 500 inoz 23 stepper mounted to a plate which is attached to the mill head. There is a preload bearing in the mounting block and have no backlash.

Acceleration can become important...ie; For 3d milling you can a have a lot of small
moves in combination moves.

Size wise, the experience from reliable users for stepppers / motors  which provide satisfactory service for "what you want to do" for a "very" similar sized machine is good advice.

If one were to "design" what they want, they would define desired  preformance,calc's would be done, consider experience of others, etc. That will provide confidence in what will be done. It gets rid of the subjectivity in doing the conversion.
Today there are manny programs to assist in doing design as compared to years past
where all was done manualy.

Just some thoughts....

RICH

920
TOOL SHARPENER
Not much CNC work as this was a build as you go kind of project.

I have a Darex end mill sharpener and it works great and also use A Foley saw sharpenener as a bench grinder, but,
never used the Foley much because the grinding dust went everywhere.
Shop space is rather limited.

As the used / chipped / broken carbide end mills and lathe tools start to pile up wanted something to prep them for finish grinding.

So started looking at all that "stuff" one collects over time to see what could be used to  make some general use carbide grinding fixtures.

Some thoughts on the matter included:
1. Cheap / "this is not going to cost much" ( hobbiest creed!)
2. Use the "stuff" you have
3. Must be easy to setup, rather accurate to minimise use of expensive diamond
   wheels for rough sharpening.
4. Be able to sharpen carbide lathe tools including inserts and end preparation  
   of broken / chipped / end mills.
5. Keep it small, is movable, and can be easily stored away.
 
So the attached file shows some of the things made.

Note: When you make a fixture the mounting needs to be accurately done as that provides for easy and accurate setup. Keep things symetrical about drilling, based plates
square etc.

SAFETY NOTE:
Pay attention to recomended and max rpm of wheels. Don't believe the cheap stuffs claim that it's good to 30K RPM. Test anything you make for runout and vibration. I put a rated 35K small wheel in a bench mounted die grinder and it went into vibration at about 15K bending the tool steel arbor ...almost jumped off the bench ( it was rigidly clamped down). Be carefull!  

RICH

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