# Toolpost Needle Valve Grinder



## Brian Rupnow (Mar 9, 2013)

I have to create a tool to grind needle valves. I simply can not turn something as small as I need on my 10" lathe. All of these small engines I build call for a #2-56 threaded needle valve with a 30 degree included angle taper, and I have no way to make one. Necessity is the mother of invention, and although I wouldn't be so bold as to say I invented this,  some of you may be interested enough to follow along. The tool in the picture is a Dremel "clone" sold by Canadian Tire in Canada. Its not a bad little grinder, but its only good for freehand work. I am going to build a mount to hold it securely in my quickchange toolpost. Its too light to do any serious work with, but I bet it will be just fine for grinding very small valve faces and needle points onto #2-56 bolts. The mounting bracket I design and build is going to be quick, and its going to be free. More tomorrow.


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## Mike N (Mar 9, 2013)

I use my cordless drill to spin the needle stem against my 1" vertical belt sander.  I also use this method to round off the corners of sharp pins & screws that I have cutoff.


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## ShedBoy (Mar 10, 2013)

I made a similar thing to what you are making. Check the nose of that thing to see if the bit behind the chuck unscrews. The dremel has a thread under there and it is quite a simple process after that. You will find many uses for it once you do it. I wil be watching along.

Brock


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## Brian Rupnow (Mar 10, 2013)

I'll start this out with a quick 3D model of the grinder I have. It is dimensionally correct, and as I have to do a small amount of layout work I will need this.


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## Brian Rupnow (Mar 10, 2013)

We'll also need one of the tool holders from my quick change tool post.


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## Brian Rupnow (Mar 10, 2013)

The next thing we do is take a peice of wood 1 1/2" thick---pine, spruce, or hardwood, doesn't really matter. We have to cut a hole in the center that exactly natches the profile of the die grinder. That will be the toughest part of this whole build. I got lucky---My die grinder is two half circles 1.95" in diameter seperated by a straight section 0.175" long, (as measured by my calipers) so it is an easy profile to recreate. If your tool has a more complex profile in the area to be clamped, you may have to use a glue gun and small bits of cardboard to copy te exact profile. (I can explain more about how to do that if you need it.) The block of wood will have a sawcut through one side, and be drilled through for a 3/8" clamp bolt. You can't see it, but I have put a counterbore in the far side of my wooden block so I can epoxy a 3/8" steel nut into it.


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## johnmcc69 (Mar 10, 2013)

Cool project Brian, do you think there may be a benefit in it to do I.D. (internal) grinding?

John


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## Brian Rupnow (Mar 10, 2013)

Next up will be to make an aluminum part, which in my case turns out to be 1 1/2" x 3.45" x 3/8" thick. It is drilled and countersunk 8 places for woodscrews to go into the wooden block. From the other side, it has two counterborres holes thru on center for 1/4" shcs. It is screwed with #10 wood screws to the side of the wooden block opposite the sawcut. Keep the woodscrews just short enough that they don't breal thru into the cut out for the grinder. For a really strong connection, run the screws in, back them out and coat them with 2 part epoxy, then run them back in.


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## Brian Rupnow (Mar 10, 2013)

The last piece to build will be made from mild steel. In my case it is 1/2" thick x 5/8" deep x 3" long. It has two 1/4"-20 unc holes tapped in it to line up with the c'bored holes in the piece screwed to the wood. I forgot to tell you---Its a trick!!! Bolt the steel and aluminum parts together BEFORE you screw the aluminum piece to the wood.


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## Brian Rupnow (Mar 10, 2013)

Now, if you have lead a pure life like I have, and all your stars are aligned, it will fit into your tool holder like this, it will be height adjustable to be exactly on the horizontal center of your chuck (I checked on mine) and it will be adjustable to any angle. More after lunch!!!


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## CNC-Joe (Mar 10, 2013)

Thanks for posting that, Brian.
- It's nice that you're posting your work so that everyone can benefit from it.

What CAD system are you using ?

Joe


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## Brian Rupnow (Mar 10, 2013)

Solidworks.


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## Brian Rupnow (Mar 10, 2013)

johnmcc69 said:


> Cool project Brian, do you think there may be a benefit in it to do I.D. (internal) grinding?
> 
> John


No John---I repeat myself---This is not for any medium or heavy grinding jobs. It ONLY has any value for accurately grinding SMALL things. The motor simply doesn't have enough power to do much beyond carburetor needles and very small (as in 3/8" diameter) valve faces.----Brian


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## Brian Rupnow (Mar 10, 2013)

Don't get the notion that I'm totally altruistic. I have to make these drawings so I can make the parts myself. Have fun. I'll post a pic and a review of how it worked (or didn't work) after I make it.---Brian


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## Brian Rupnow (Mar 11, 2013)

I am editing my post to say that this great experiment didn't work worth poop!!! It seemed like a great idea, and my first results were promising, but there is simply too much flex and wobble in the set up to really do any worthwhile work. Sorry about the formerly positive comments. I was mistaken. Oh well, Nothing ventured, Nothing gained..---Brian


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## Charles Lamont (Mar 11, 2013)

My version, for a die grinder, is at the foot of this page:

http://www.charleslamont.me.uk/iqc_toolpost4.htm

Your tool looks as though, like my Dremel,  it has a threaded end with a cap/nut over it at the business end, behind the chuck.
To set this up for a grinding job, I bolted an angle plate to the cross-slide boring table, bolted a bit of 1/8" plate to that, and poked a hole in it to take the Dremel. 2nd photo
on this page:

http://www.charleslamont.me.uk/Seagull/drive_coupling.html


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## Brian Rupnow (Mar 11, 2013)

Charles--Yours looks sturdier than mine. Mine is all made of plastic, even the screw on nose cone and threads. Now that I've had a chance to use mine a bit more, I'm not nearly as impressed with the results. I wouldn't really recomend anyone build this. It doesn't cost anything but your time, but sadly the results aren't as good as I had first thought.---Brian


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## jixxerbill (Mar 11, 2013)

I have thought many times about trying to make a grinder like that Brian. But mounting it always seems to be what changes my mind.. I saw this last time i was at HF, I started to buy it but didnt.. I think it could be mounted alot easier, but requires air instead of electricity..Bill
http://www.harborfreight.com/1-8-eighth-inch-air-micro-die-grinder-47869.html


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## petertha (Mar 11, 2013)

Brian, did you see this post?
http://modelenginenews.org/techniques/needles.html

I noticed you used a cylindrical grinder. Is it making continous contact on the taper & maybe why its bending back teh stock from pressure? Maybe it would be better to use a disk style grinder, lighter grit & finer feed. A disk would run along the taper & only cutting a smaller portion at a time so less bending force? Kind of like sharp lathe bit contact vs big flat cutting surface principle?

FWIW, my experience with grinding stones typically packaged in offshore moto-tool kits must be made from bits of sidewalk cement.  They cut crappy, heat the material & seem to clog easy. I bought some good quality rotary stones from a jewely supply place & they were like night & day difference (on hardened pin shafts). Dont recall what they were but they come in an assortment of colors like grinding wheels. They didnt cost that much & offered dozens of styles to choose from.

Is there any way to support the end of the wire in a makeshift tailstock to stop flex? Even a block with a hole in it? Maybe you could grind the majority of taper in a mid section & then lop off the end so it stays supported as long as possible?


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## Charles Lamont (Mar 11, 2013)

Brian Rupnow said:


> Yours looks sturdier than mine. Mine is all made of plastic, even the screw on nose cone and threads.



The Dremel is the same, and I was a bit concerned, but it turns out to be strong enough to make a perfectly adequate mounting.


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## GWRdriver (Mar 11, 2013)

Brian,
I just now tuned in and had I arrived sooner would have reported that this scheme never worked for me.  I have to qualify my statement by saying that what I wanted to achieve was a substitute toolpost grinder and even the best Dremel or Dremel-clone tools (specifically their bearings) aren't up to the job.  The reason is just as you have discovered, there is too much flex and runout in the cheap spindle.

I'm not exactly sure what you need to accomplish - is this a shaping operation or a finishing operation?  If it's a shaping (ie, turning) operation and what you need is increased spindle speed I would start to think in terms of an accessory spindle which would mount in your lathe spindle nose and be driven by a small high speed motor & belt.

Tell me more before I wander way off course.


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## Lakc (Mar 12, 2013)

Indeed, tried myself and learned long ago. It was an interesting experiment, but now you know why they charge so much for machine tool grade bearings. Small rotary tools wont cut it for a precision application. 
Now if you want to create a wide toolholder that can take perhaps 1.5" od bearings (tapered roller?), and make a custom spindle with a simple belt drive,  it might be reasonably cheap and effective. That's "on my list" for a go eventually.


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## Mike N (Mar 12, 2013)

jixxerbill said:


> I have thought many times about trying to make a grinder like that Brian. But mounting it always seems to be what changes my mind.. I saw this last time i was at HF, I started to buy it but didnt.. I think it could be mounted alot easier, but requires air instead of electricity..Bill
> http://www.harborfreight.com/1-8-eighth-inch-air-micro-die-grinder-47869.html


I used this exact one from HF on the little toolpost grinder I made, it fits right into the Aloris style tool bit holder without any modification.  I use diamond cutters instead of abrasive wheels that seem to bounce all over the place.


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## Art K (Mar 12, 2013)

Hi Brian,
Just caught your needle valve grinder. That's a great idea, I wouldn't have thought of. I will keep it in mind next time I build a carb.
Art


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## Brian Rupnow (Mar 13, 2013)

Art K said:


> Hi Brian,
> Just caught your needle valve grinder. That's a great idea, I wouldn't have thought of. I will keep it in mind next time I build a carb.
> Art


 
Art K---You might want to re-read post 15.--Its a great idea but it didn't work.---Brian


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## AUTO_XX (Mar 24, 2013)

I did one a couple of months ago to bore a 1/4" inside groove with an endmill 3/4 deep.  There was a bit of chatter if I didn't get enough WD40 (handy for aluminum) but apart from that it worked great.
It's also a "must-have" item for polishing. You can bring a mirror finish up in just a few seconds.
The surface finish isn't as nice as turning with the lathe tooling but it was liveable.


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## rayjones (Mar 25, 2013)

Nice work Brian. I have a 3/8 Hitachi battery drill (drill in good condition, batteries expired). I also have a DC power supply which
will power the drill. With not too much work, I will have a tool post drill.

Regards Ray Jones


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## Brian Rupnow (Jun 6, 2013)

So----Today I'm in time killing mode. The toolpost grinder that I tried to make by holding the Dremel tool in a wooden block was a dismal failure. Oh well, it didn't cost me anything, and nothing was hurt but my pride. Today I took the time to make a metal holder for my much sturdier all metal ARO air grinder. It works.---At least it doesn't jump and wiggle around when used----Its very sturdy. I realize that there is an entire world of things I don't know about grinding in a lathe. I do know its not good for the ways, so they should be protected when doing this. I know there are proper mounted point style stones (all I have today is that cheesy cut off wheel in the pictures) and that they should always be trued with a diamond? or something before each use. I have a lot of reading to do, to study up on this entire business. There is nothing in particular that I want to grind---except maybe the pilot on all of my counterbore tools.--They are always much larger than the holes I generally use for clearance holes when model building. --Perhaps if I ever get bold enough to build another i.c. engine, I could grind the valve faces. Oh well, I've killed  half a day, and that's what this was about as much as anything.---Brian


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## Lakc (Jun 6, 2013)

Wtg Brian. Give it some more testing and let us know how well it works. 
My thoughts have returned to this idea as well, as I have a cast iron crankshaft that is a little chilled and too hard, and I could use any old grinder type setup to just get past the skin on it.


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