Thread: Drill Grinder. 4 6 Facet.

Hi Guys,

I have decided to build "John Morans" 4/6 Facet drill grinder following receiving build notes from John and encouragement from Bob (krisfarm).

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So since collecting bits and pieces of material is part of a project and a suitable motor is required for this one, I went hunting around in my local scrapyard for one.

Unfortunately my first find turned out to be no good, so it got taken back and thrown away. I found two more motors, one looked quite clean and new looking and the other a shower pump that seems quite substantial. Someone had removed the brass impeller housings but the rotor seemed to move freely and it didn't look or smell burnt.

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This motor measured 130 watts no load and seems to be very quiet and smooth running. It has sealed bearings at both ends. The shaft diameter is 11.5 mm. It is also reversible by swapping one wire. It did occur to me that it might be dual speed but not so. Its difficult to see but the motor frames are riveted together so a bearing failure would probably mean scrapping the whole thing.

I did notice that an awful lot of the motors that I saw in the scrap yard had this same riveted together construction. Something that you don't find on motors intended for industrial use.

I don't have a tachometer yet, one on order, so I can only guess at the speed. It seems slow so it could be a four or even a six pole motor rather than a preferred two pole one. All the red pen markings are mine from the short testing that I did.

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This motor came from a discarded shower pump and is almost certainly a two pole machine. Unlike the other motor this one is not reversible and only has sleeve bearings for the shaft which is spring loaded at one end and is 8.5 mm diameter. It is also very noisy and vibrates badly compared to the other motor. So shaft balance is questionable.

My preferred motor would be the first one as long as the motor speed is high enough. Both motors are capacitor start and run, neither has a centrifugal switch.

Thanks:

Hi Guys,

Whilst playing around with the motors I picked up the other day, I did wonder why the first one was so clean and in excellent condition. Anyway whilst taking measurements for the size and mounting positions, I noticed this !

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It seems that the shaft had some kind of threaded end, possibly for a nut or threaded pulley of some description and it has sheared off at the root.

Because of its riveted together construction it wasn't reparable and so scrapped. However the relatively long shafts allow for its re-purposing.

Hi Guys,

Still collecting bits and playing about with the motors.

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I decided to take the cover of the shower pump motor and put a longer length of cable on it. I have discovered that it has a triac in series with the motor and that it can be switched on/off remotely. I have also found that this motor too can be reversed by swapping two wires over. The motor was made by "Gundfoss" for Deva Tap Company.

Originally Posted by BaronJ

Hi Guys,

Still collecting bits and playing about with the motors.

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I decided to take the cover of the shower pump motor and put a longer length of cable on it. I have discovered that it has a triac in series with the motor and that it can be switched on/off remotely. I have also found that this motor too can be reversed by swapping two wires over. The motor was made by "Gundfoss" for Deva Tap Company.

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I've quoted the earlier post to add this photograph of the circuit board hiding under the motor cable cover.

The Live, Neutral and Earth connections come in at the right hand side with the four motor connections on the left. The green wire is the earth and is connected to the metal frame via a riveted ring terminal.

The red wire goes to the triac. The motor windings have one end connected to the blue and white wires, the other ends go to the red wire.

The two wires at the bottom of the picture go to the capacitor and are connected to the blue and white wires. Both windings have the same resistance and so are identical. Moving the neutral wire from blue to white makes the motor run the other way.

Thanks guys.

Hi Guys,

Now I've got the circuit board in the shower pump motor out of the way, It's time to let you know that the Digital Tachometer that I ordered from China, turned up today. Whew, that was quick...

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This was ordered on the 11/02/2016 and cost less that £10. Having now checked the speed of my preferred motor and found that it spins at 2950 rpm, I'm happy. I had visions of having to build a spindle and a step up drive.

Onto the Tool Holder. I have an ER16 collet holder and collets that I intend to use and a nice chunk of hexagonal brass bar 32 mm across flats. I parted off a 63.5 mm long piece and drilled a 17 mm hole right through it. I then used my rather small boring bar to open up the bore. I stopped when I realised that the bore was becoming quite tapered due to the flexing because of the long overhang. So I found a bit of key steel and made a new one. This one is far more substantial and doesn't flex over the length of the bore. I used a broken 3.5 mm drill for the toolbit.

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I used a 1/4" whit grub screw in the end to hold the toolbit
I also made a 20 mm diameter plug gauge so I could test the bore.

Whilst I was turning bits and pieces I parted off a 1/2" slice of 40 mm diameter bronze bar that I found at the scrap yard. This also was drilled and bored 20 mm. Another item that I made was a plug so that I could hold the piece of bronze, now a ring, in order to mill a groove in it for the index pin.

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The pictures show the bored out tool holder with a 3 mm pin pressed in, the index ring along with the plug gauge. The initial two 3 mm holes drilled with their centers on a line across the diameter and the index ring machined with the 3.2 mm wide slot for the pin to travel in.

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These two pictures show the milling process. I made a mandrel with an M6 threaded hole and an aluminum clamp to hold the index ring securely onto the mandrel. The slot drill is a 3mm one with a 6 mm depth of cut. It only just reaches the depth required.

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These pictures show the trial fitting of the collet holder, the index ring and tool holder.

The index ring needs to have a clamp screw fitted and an adjusting screw for the depth.

Thanks for looking guys. Comments welcome

Hi BaronJ,
That shower pump motor looks like it will do the job for you,a nice pickup. Do you intend running it clockwise or anti clockwise? Either direction will work OK but in your build as you have used a hexagon section for your chuck I think it would be better to turn clockwise as the base on your hexagon chuck is not very wide. Turning clockwise will keep the chuck pressed against the base, anti clockwise will make it want to lift off. My one does require a firm grip to hold it in place and it is a lot wider. If you think this is a concern you could always add a wider base onto your hexagon section.The bronze/brass combination should be a nice combination sliding on the collet chuck shaft. Nice machining job on the fittings. Brass is nice to machine but it is a messy operation.
Bob

Good morning Bob,

Thankyou for your comments.

Now that I know the speed of the first motor, 2850 rpm, and that it is much more smooth and quiet running than the shower pump motor, I intend to use that one. Also the shaft is bigger in diameter so more rigid.

I'm not quite sure what I'm going to do about the rather small face size on the tool block at the moment. Adding a broader base is an option that I will probably go for. I realise that I haven't a lot of meat to work with.

That bronze is tough stuff, the brass not so bad, but as you say very messy, lots of fine swarf scattered all over the place. I have some 20 mm diameter bits of brass that started life as shear pins, that I intend to use to make the two M5 thumb screws. The depth screw does bother me a little, there is very little room for a spring and the screw head there.

I'll post some more pictures as I progress.

Hi BaronJ,
That 2850 rpm motor is the one I intended,I got your motors mixed up, my mistake. The larger shaft will be more rigid,the cone wheel is quite heavy. For the base widening you could fold up a 90 degree angle out of a piece of brass sheet around 2mm thick with a nice radius in the corner as it would clear the hexagon and use some of your smaller sized BA counter sunk screws to attach it. The knurled knobs on my grinder are only 13mm in diameter and this is large enough,and have 4mm threads.The adjuster screw is has a 3mm thread, I just used a long phillips head screw that I machined the diameter down a little on. You only make 1/4 turn adjustments on this when grinding. You could go to a smaller thread size if needed.
Bob

Hi Bob, Guys,

Just a few pictures of the shear pins that I used to make the M5 thumbscrews for the index ring and collet spindle locks.

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These are the two shear pin half's that I used to make the thumbscrews.
I understand that these are used on a 10KW generator drive coupling from a diesel engine.

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Both thumbscrews are M5 threads and are 10 mm diameter X 5 mm thick. The two different threaded lengths are because I didn't want the screws to stick up excessively. The knurling isn't as nice as I would like, I'm still learning how to do it properly.

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The knurling on the index ring is horrible. I have a home made clamp knurler using a pair of wheels that I salvaged from a bump knurling tool.
When I started to clamp down on this one it ran across the surface pulling the saddle with it.

If you look carefully at the bottom middle picture you can see some slight score marks from a bit of brass swarf between the collet holder and the tool holder bore. I scraped the burr off the inside of the index ring but can't reach on the tool block with a scraper. I've been thinking about trying to get at it with the Dremal and a small wheel.

Next job is to make the frame to mount the motor. I've got some bits of 3mm plate that I can use.

Bob: Sorry, I forgot to answer your question about motor direction. I intend to use a center Off three position switch so I can run the motor either way.

Thanks Guys.

Hi All,

I was at the scrap yard again yesterday looking for some more bits and pieces. I picked up a foot of 50 X 50 X 3 mm angle iron and an 180 mm long chunk of 10 mm thick by 50 mm wide stainless steel bar along with another shower pump motor.

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As can be seen from the label on the motor it is 525 Watts and 2800 rpm.
A standard capacitor start and run motor that can be reversed by swapping the mains neutral wire to the other side of the capacitor. This seems to be quite common for this class of motor.

It has been stood out in the rain but apart from the sized pump, which I've already removed, runs quietly and smoothly. It has a steel plate foot with quite large mounting holes hidden under a pair of flexible rubber mountings.

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It seems to be a common feature of these pumps to have some kind of remote control system. This one has a relay which when activated delays the motor start by about 1.5 seconds. The two brown wires go to an external control switch that measures the feed water pressure. Unless the pressure is high the motor won't start. Probably a safety mechanism to prevent the pump running dry.

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As can be seen the shaft has a key that locks the shaft and impeller together. The fan on the other end is a simple push on device and along with the cover directs airflow over the motor body. This motor does not have any vents or through holes for air to pass through it, so it should be quite clean inside.

It is a nice ball race mounted rotor and worthy of refurbishment, however no use for this project I'm afraid. The end of the motor shaft, which is 10 mm diameter, is slightly bent. There is a 5 thou wobble, measured on the body side of the circlip groove. It probably got bent when I was pulling the sized pump impeller off the shaft, though I didn't realise it at the time.

Thanks Guys.

Hi Guys,

After thinking about the tool block and the way that a screw is used to adjust the amount of material that is removed from the workpiece, bearing in mind that the tool block is going to have to be raised up from the table to align it with the wheel center height, I thought that making a dovetail slide could be a good Idea. Particularly since I would like the ability to sharpen other toolbits as well as drills.

I did a drawing showing what I have in mind.

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The dimensions are based on the bit of stainless steel that I picked up the other day. I have plenty of 3 mm brass and steel plate. An M6 screw would give me 1 mm / 39.4 thou movement per turn.

What does anybody think... I'm away all next week so nothing is going to get done until I get back.

Thanks all.

Hi BaronJ.
I am not quite sure of your other intended uses for the drill sharpener are and cannot work out how this intended dovetail slide would work. Do you plan on cutting a dovetail into a piece of stainless steel ? This will be a challenge as stainless work hardens and taking light cuts with a dovetail cutter will harden it real quick.The centre line of the collet has to be aligned with the centre line of the pivot axis, not the grinding wheel center height. The face of the grinding wheel also must align vertically with center line of the pivot axis as well.
I assume that you have selected a M6 screw for fast adjustment and would use a much finer thread for your actual grinding adjustment.These grinders can only remove a small amount with each pass, I have found a cut of .005" to be the maximum, I mostly only take of .002"-.003". My in feed screw is 3mm *0 .5mm pitch ie .020" per turn and a quarter turn or less is all that is needed.
Bob

Hi Bob,

Sorry for the slow reply, only got back home this morning. Spending time visiting Daughter and Granddaughter No:2.

Thank you for the notes about alignments. I had got it into my head that all three axis had to be aligned correctly.

I was thinking that I could also sharpen end mills or slot drills as well as ordinary twist drills. As far as the dovetail slide is concerned the bits in green would be brass plate fastened down with screws to form the actual sliding surfaces. I thought that it would make use of the space under the tool block. Now I see that I don't have to raise it up.

Next job is making the mounting brackets for the motor. Two 100 mm lengths of 50 X 50 mm X 3 mm angle Iron with 14 mm holes drilled and then filed out square to fit the rubber mounts. I'll take some pictures of them when I've done them. I hope to be able to get a few offcuts of 5 or 6 mm thick steel plate next week.

Thanks:

Hi BaronJ,
Good to hear that you did have the alignment correct, I thought you would have. I seem to remember that John Moran had his original motor rubber mounted but he did not like it and replaced it with a solid mounted one. I did the same and removed the rubber feet from mine and bolted down solid, food for thought for you. I have added two additional chuck mounting holes to my grinder to allow me to sharpen slot drills. I will take a few pictures later today, have to go now.
Bob

Been following this thread with interest. Hope you don't mind if I jump in with a question.

I have some ER20 collets and a straight shaft holder and thought I might have a go at this sharpener.

What sort of wheel is needed? This is what I think but am not sure.

75mm Bowl Carbide Metal Diamond Grinding Wheel CUP 180 Grit Cutter Grinder Tool | eBay

75mm Bowl Carbide Metal Diamond Grinding Wheel Cup 180 Grit

Or is it more like this?

4''100mm Diamond Coated Rotary Grinding Round Wheel Disc CUP FOR Tool Cutter AU | eBay
4''100mm Diamond Coated Rotary Grinding Round Wheel Disc Cup For Tool Cutter

Thanks for any help.

EDIT: I should mention I only see it being used for HSS sharpening. Not carbide.