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Messages - FlashGP

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1
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 11, 2019, 08:36:32 AM »
Hi Makky,
It's a thought, but if I change, it'll be to one with a morse taper.
I have a mate who is a fitter and turner who is talking about sleaving and boring out the hole for the motor shaft to 0.01mm larger than the shaft.

I'm hoping to find a solution that doesn't need access to a lathe so the design can be built by anyone.  Im contemplating putting 3 grub screws in the collet holder so the slop at the end of the motor shaft mounting can be used to adjust the centring of the taper for the collets.

Regards
Gordon

2
Tips and Gadgets / Re: The best "bits"?
« on: January 09, 2019, 10:46:42 PM »
Harryopal had a good point about the dust if the work is not kept wet. 


There's currently an outbreak of silicosis in Qld among the Stone Masons cutting and finishing stone bench tops.  I can't believe they have been doing this dry, especially with re-constituted stone.


I heard one press report of 27 cases in a hand full of work shops, enough for the Minister to ask for a ban on imported re-constituted stone. 


It surprises me that is the only reported action, I would have expected the Workplace Safety Officers to be treating these workplaces the same as a workplace handling hazardous materials.


I'm also awaiting to see if there will be criminal prosecutions under the WHS laws or the outcome of civil claims relating to a foreseeable danger to the worker's health, that could have been avoided using cheap wet cutting and grinding techniques.


Regards

3
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 09, 2019, 10:25:07 PM »
Hi Makky, my ER11A arrived in today's post along with a set of 1 to 7mm colletts.


The 1/4 inch collett snapped into the new collett nut and I don't know how to get it out.  The Collett nut fits both the ER11 and ER11A collett holder so it shouldn't matter.


The motor shaft fits into the end of the ER11A collett holder neater than the ER11 collett holder, but the tooling (cutting mandrel) wobbles about 1 to 1.5mm at the end when put in the new ER11A collett holder.  An allen key held at continuous sections of the collett holder produced a it of chatter and the end of the collett holder also seems to be wobbling a bit.  I suspect concentricity of the bore for the motor shaft is the issue here, (assuming the taper is ground concetrically.


When I put the old ER11 collett holder back on the motor shaft with the new collett nut and 1/4 inch collett, the tooling did not appear to wobble.  Changing the tooling produced a smaller visable wobble than the ER11A.  Backing off the nut and rotating the collett and tooling before re-tightening the nut seemed to cure this issue, but there is a small amount of chatter. 


This ER11 Collet holder is the original collett holder that I ground out a little using some 1200 sandpaper wrapped around the 1/4 inch collett and pushed into the spinning taper.  I did this to make it release the collett easier after I had drilled out the flange inside the collett nut that pushes the collett out of the taper as you unscrew the nut (because I didn't know better and it seemed too small to allow the collett head to pass through it and mate with the taper inside the front of the collett nut).


I have still to take some measurements and see where the problem lies, but I think it is: 1. allignment of the chuck on the motor shaft, and 2, high spots inside the taper.


Regards
Flash

4
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 09, 2019, 06:56:09 PM »
Ah, yes,

I bought the 1/4 and 1/8 inch collets separately from the collet holder and nut.  They had run out of sets of 1 to 7mm collets and collet chuck.

Gearloose's shaft on his mandrel is a full 1/4 inch so the 1/4 inch collet is a snug fit.

I couldn't fit the collet into the flange inside the collet nut so bored out the flange si I could assemble the unit. 

I have an ER11A on order.  Will see if that improves things.

5
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 07, 2019, 10:32:54 AM »
Hi Makky,

the mandrel runs true in the chuck of my bench drill.

I wrapped a single layer of alfoil inside the hole for the base of the collet holder. 

This removed some of the vibration by redicing the gap between the collet holder and motor shaft, but the wobble on the mandrel is far greater than the vibration on the outside of the mandrel holder.

I have a second mandrel holder on the way and will see if I get similar results with it. 

I was going to borrow a dial indicator from an engineer mate to check for concentricity in the collet holder.  It would only take a high spot to throw it out.  But I realised I can check this with the dial indicator on my mast by setting the cutting angle to 90 degrees.

Am thinking that if the shaft play is the cause of my woes, I may need to drill and tap 3 allignment grub Screws at the opposite end of the motor shaft holder.

regards
Gordon

6
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 02, 2019, 11:58:18 PM »
Thanks Makky,


I've managed to tune it so the cutting mandrel runs parallel to the direction of travel by adjusting the bolts holding the motor bracket.  I also placed a shim under the front of the motor bracket so the dial indicator barely moves when the unit oscillates but with the motor turned off. 


The body of the ER11 Collet chuck spins with very little error, but when a mandrel is placed in it, the mandrel runs out and vibrates the dial indicator.  I may have to out the body of the collet chuck in a lathe and make sure the taper holding the collet is running true.


I've ordered a second collet chuck to see if it makes a difference.  Otherwise I'm pretty happy with it.


Let me know if you have any queries regarding it.  The cost of a patent is too great for the anticipated market, but I'm happy to share the idea with anyone wanting to make one. 


happy faceting
Gordon

7
Tips and Gadgets / Re: The best "bits"?
« on: January 02, 2019, 07:02:41 PM »
I have a couple of diamond plated twist drills for enlarging holes in stones.  they cost me about $35 from AJS and are 1mm and 1.2mm.  The 1mm drill has cut a few holes but is wearing.


We always use hem in a water bath.  Are you drilling under water or dry? Drilling dry will wear your bit out really fast.


regards
Flash.



8
Gemstone Faceting / Re: Prototype Concave Cutter
« on: January 02, 2019, 06:59:33 PM »
Thanks Rusted,


The little geared motor works fine to drive the oscillator.  However I am not sure how long it will last.  I'm going to buy a spare just in case, with shipping they cost under $15.  A microwave turntable motor is only 2W, but 240VAC.  It's safer to use a 12v DC motor.


If the oscillator speed is turned down, the motor stalls if the carriage hits something.  Hopefully this will prevent serious injury if a finger gets in the way, or the stone runs off the end of the Mandrel.


regards
Flash
 

9
Gemstone Faceting / Prototype Concave Cutter
« on: January 02, 2019, 05:21:39 PM »
I finally finished my budget concave cutter.  I have embedded links to photos in the Gallery.  click on the link to view them.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9017

I don't have a lathe or mill so designed the cutter to be adjusted in the y Axis (the mast moves in the X axis).  There's 25mm of play each side of centre.  This means that I can cut parallel lines on the side of a step cut by moving the mast out of alignment for cuts other than the first.  The adjuster thread advances 2mm per turn. I used anti backlash nuts on the threads to remove the slop in them.

The parts cost me between $450 and $500 to make, before cutting mandrels.  I used linear bearings to support plywood decks that sit around the platten on my Factron.  I used 4mm T Nuts to pressed into the Ply as ancker points, although the lower bearings and alignment screw are sitting on 3mm angle aluminium. 

I made the arm on the oscillator motor from a piece of 10mm square mild steel, drilled, tapped and cut down.  3 taps at 10mm, 15mm and 20mm from the centre means that I can adjust the throw on the oscillator between 20mm and 40mm to accommodate different mandrel sizes.  The link is two tie rod ends for CNC Cuters, one male and one female.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9020

I bought a cheap Ryobi laser level and Stud Finder at the post Christmas sale.  The laser level throws the laser in a vertical arc so it produces a line on a surface.  Here I'm using it to sight down the middle of the cutting mandrel and shine on the mast.  If the cutter is out of alignment, two lines appear on the mast as in the picture, as the cutter is brought into alignment they merge into one bright line.  I'm pretty sure this has something to do with the reflection from the curved surface of the mast.  Once the mast is aligned, the Quill is lowered and the Quill Stop adjusted until the laser is shining down the centre of the Quill.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9021
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9025

I used a 25 amp switch mode supply with 2 10 amp pulse width modulators for speed control of the cutting motor and the oscillator drive.  I only needed a 10 amp supply, but the price difference means was small and I can use the Power supply to drive larger motors in need.  The motors I am using only pull 4 amps between them.

http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9023
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9024
One of the PWM modules is reversible, it is the one standing on edge, the other cost $3.60 and I am trying it out.  It seems to work OK.  I had to de-solder the Pot on that  module and add 3 signal wires so I could mount it as the box I purchased was a little small.  The resistor in the photo is a 10w 22 ohm power resistor to keep a 1/2 amp current flowing.  This is to stop the power supply going into overvoltage when the motors are turned off.  All up the Power supply cost me almost $100 and  it has the grunt to drive 2 x 90w motors.

10
Fossicking Locations / Re: Rock to tumbling in Samford/Dayboro area
« on: December 30, 2018, 11:14:18 PM »
Hi LukeFly,

On the Left Hand Side of the pier at Redcliffe (if you are facing the water) are some red an white mud rocks with lots of little round black beads in the holes and sand around them. 

Many of the black beads look a bit like ball bearings.  They are Haematite (an iron ore) and are attracted to magnets, so take a magnet with you the kids will have fun finding it.

Haematite is named after the Greek name meaning for blood stone.  It leaves a red streak.  It polishes to a steely grey colour with a high lustre and is used in Jewellery.

Have fun.
regards
Flsah

11
Gemstone Faceting / Re: Fred W Van Sant Star Cuts 1-6 Wanted
« on: December 20, 2018, 08:30:23 AM »
There are 13 Fred VanSant diagrams in Dataview.  The AFG inhereted Evan Williams' copyright to his designs in Dataview and so has a dataview set complete with cutting instructions.  It's available to members.

12
Tips and Gadgets / Re: Gemmasta Encoder Mod Thread
« on: December 17, 2018, 06:59:43 PM »
Thanks Makky.  Wil follow up once I finish the Christmass presents and then my prototype concave facetor.  Mrs Flash put her foot down and requires the presents finished first. But getting close to finishing the project.

Had thought of patenting the design, but would have to sell 100 units just to cover the cost of the Australuan patent, let alone foreign patents.  It'll be easier to make the design public and try to claim copyright to the designs.  Given I don't know how durable the motors are, not having to worry about warranties is a plus.  At under $20 they are cheap enough to replace.

Regards
Gordon



13
Tips and Gadgets / Re: Gemmasta Encoder Mod Thread
« on: December 17, 2018, 09:03:35 AM »
Hi Makky,

I might take you up on that.  I haven't played with electronics for over 25 years. And it is over 30 years since I did any hex programming.

  My latest project was a twin 10 amp 12v supply for my concave prototype.  It is really just a 25a 12v swich mode supply with 2 speed controllers.  Way over rated for my motors but enough grunt to drive a couple of 90w motors in need.

I hadn't thought of hall effect sensors.  My thought was to drill a hole through the drive pully and use an opto coupler with a counter with a 1hz window before it resets.

Regards
Flash

14
Tips and Gadgets / Re: One At A Time - Please!
« on: December 17, 2018, 08:43:37 AM »
Hi Makky,  I agree with your last comment regarding accuracy.  My mates' mill is calibrated to 0.001mm, but it weighs several tonne, ex TAFE equipment.

However some home engineers will be good enough to make a CNC cutter accurate enough for the job.  The bigger issue would be presssure sensors so the stone isnt squashed on the lap.

I just threw my earlier comment half in jest.  Whenyou think about it, faceting machines are really just prescision grinders. 


15
Tips and Gadgets / Re: Gemmasta Encoder Mod Thread
« on: December 16, 2018, 10:03:55 AM »
Hi Makky, I haven't gone down the path of digitising my machine yet, since the Facetron has dial up angles, I haven't been bothered as I have printed a 1/100th scale that works ok. 

But I am thinking of making a tacco for the lap speed.  As my machine's speed seems way faster than most.  Minimum speed is about 60 to 100 rpm.  I am not sure if I am exceeding the maximum RPM on some of my laps. 

How did you implement the RPM counter on your conversion?
Have you found it useful?

The alternative is to use a strobe to measure/check lap speed at the dial settings and mark the position of the maximum lap speeds on my dial.

regards
Flash


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