Member postings for Dave S

My father has such an Ivory Puzzle ball. I think it came from China, but my family has some connections with India, so maybe it’s from there.

Dave

Whilst I have an adjustable frame I have never felt the need to adjust it.

Quality blades do make a difference. I’m currently using Super Pike from Cookson Gold for most things.

Their platinum blades hold up better than normal ones for stainless and shin steel.

Dave

For the original question: I hold the blank in mole grips.

As for the dip in water or you’ll ruin it: Rubbish.

The “to hot to hold” temperature is around 50C IIRC ( Had to research this for a product at work) Way less than HSS annealing temps.

If you can get a HSS blank to annealing temps and hold it there on an offhand grinder then I’ll be amazed...

I used to grind slow and dip when I started, but then I gave it some thought.

Try abusing a piece of HSS - I have and it’s still as hard with blue temper colours on it. Most of my HSS tools have some tempering colour on them.

if you want a really sharp tool then grind it hard and fast, then hone it on a diamond bench stone. You’ll be making chips faster than the fussy man (it’s usually a man) who will still be faffing to not over heat his HSS.

One problem is that Starey et al were writing before HSS was commonly used in the home workshop. Sure if you grind a silver steel or carbon steel tool to blue you have drawn the temper and it won’t be as hard.
There is a lot of received wisdom in model engineering which is actually history and no longer accurate IMO

Dave

If you are losing the edge on your cutter rapidly that suggests either the heat treat was not good or you are running it too hard and this drawing the temper, which leads to softening, which then rubs and heats and so on in an unfortunate feedback loop. Are you using cutting oil? How fast are you turning the tool and what feed rate?

My silver steel cutters were a bit hit and miss until I bought an enamelling kiln. I didn’t buy it for heat treating, but it goes hot enough, is pretty well controlled on the temperature and is convenient as it’s in the workshop anyway.
Since I started to use it for heat treat my hardened parts have been much better and more consistent. Not suggesting you need a heat treat oven, but judging temperature by eye on a scaled up piece in a flame is not a thing I ever mastered...

Coventry Grinders sell quality Silver steel at reasonable price.

Dave

It becomes second nature after a period.

Im not sure right now (at work) which way turning does what, but I know if I’m stood in front of my machines I can “just” use them.

This became very obvious when I bought a cheap x-y table to make a cutter grinder.
The cheap table had RH threads on both axis. It only took a couple of oops moments for me to change the Y one to LH to match all proper mills...

Dave

The quill stop on my TOS just used 2 "nuts", which you lock together using finger pressure.

They are about 1" diameter and knurled, not plain hex nuts.

Dave

You can get away with a whole lot less side relief than shown.
As little as a quick stroke with a Diamond file will be fine.

The front face can be nearly vertical.
If you a smack on center height then a vertical face would still have “relief” by virtue of the cylindrical shape of the bar.

Dave

Click spring over on YouTube has a video showing how:

**LINK**

Seems fairly straightforward

Dave

Don’t think I’ve ever used coolant on my Unimat.
I do have flood on the CVA and the Grinder, and use an oil can on the mill.

To clear swarf I keep a value tooth brush with each machine.
Having a reasonably long handle means hands clear from cutting tool, and the bristles/handle are soft enough to cut if it gets too close.

Dave

On my Unimat 4 (essentially the same) I open the belt guard and hold the pulley whilst unscrewing it.

There is a cross hole in the back of the spindle you can use to stop the spindle rotating of a gorilla has screwed on your chuck. In that case an adjustable spanner on a chuck jaw and a pin punch through the hole would do the job

Dave

I thought the point of filing buttons was that they were dead hard and so the file just skated over them?

Dave

Try holding a relatively long thin (say 0.5-1mm diameter and 10-15mm long) part to work on the end with superglue.

With shellac you can drill a hole, fill it up, warm it and then insert the part.
You can make the part run true with a little heat to soften and some careful pressing.

As with most things tool related it’s having the knowledge of the easy way which makes life simpler.

Dave

I made the ends of my grinding wheel balance arbour the size of the largest bearings I had hanging around, IIRC they were about 15mm ID/30mm OD

I flushed out the bearings with wd40 to remove all the grease and then set them into v blocks.
That is sensitive enough to detect a a small out of balance on an 8” wheel, such that the spindle weights moved together make it rotate quite quickly.

Can you make the ends of your arbour small and do a similar thing?

Dave

Evening all,

Now my CNC has potential to work nicely I'm thinking about making things

I will be making some small watch parts, mostly 2d in general shape. I think I can effectively cut these out of sheet stock, but what's the best way to fixture it?

Additionally what do you do to prevent the part breaking out and jamming/snapping the end mill.

For general size the would be parts that require 1mm or smaller endmilll to get into internal radiuses, and typically 1mm or so thick.

I occurs to me that I could use (say) 1.5 mm gage plate,surface the top by 0.25, cut around the part leaving 0.25mm bottom stock. Then fill the "gutter" with shellac and flip over, probably on my surface grinder to remove the 0.25 left.

Any better techniques?

Dave

Another method, assuming involute teeth:

Take some plasticine or other softish clay like material, create a small block on a flat surface and then roll the gear over it.

The matching rack form is then created and the pressure angle can be measured directly with a protractor from the sides of the flanks.

Dave

I stuffed the endmill into the collet further - as I could do now its ER16. This spindle is loads quieter, both cutting and idling.

I'll run the job from scratch once the bearings are sorted, but I am also interested - that should allow me to tune which is where I started this whole thing.

Dave

Good news!
My CNC failed to snap my last 2mm endmill last night
The Job started:

and then it progressed some

As it was all looking good I even went and sat in the garden with a beer, keeping an ear out for the noise.
I was back to watch the pocketing process, as the rest of the cuts were small width, and this was the full width, after all the other milling.

took just under 2h20.

End result of the roughing pass:

Somethings gone wrong here, the pocket is supposed to be a curve:

Turns out the recycled bearing on the X Axis has collapsed/ jammed.

Must have happened pretty much at the end, as the other shapes look OK.

That's why I took the stock off - cant run the finish on it until the leadscrew is sorted, which means stripping the table out...

Still, massive progress, and the new spindle seems to have made a difference.
I think its now in the 'tune' stage, rather than the throw things at it stage

Thankyou all

Dave

Many years ago I needed to do some very small precision drilling, so I bought one of ARCs ER16 high speed spindles.

That project got done and as part of workshop tidy the spindle got packed away for “later”.

I don’t think they still sell them, but similar spindles can be found out of China.

it runs of an invertor, 750w and 4-24k rpm IIRC

Bit overkill for this mill I suspect, but already in the workshop and should solve the runout issue.

Seemed worth a try for the time investment

Dave

I've had a busy weekend in the workshop:

I didn't manage to run the CNC , but I did manage to re-spindle it:

I have no idea how to drive a CNC, the little I did was many years ago. So I guessed a tool path, based on the few things I remembered being a typical clearing path as was.
I’ve never “run the numbers” as such on my manual mill, it’s built like a brick outhouse and being manual you can “feel” how the cut is going. It’s a while since I snapped a mill, iirc the last one was a 12mm rougher that I took an overly optimistic DOC into 316.

Im having a “family night” but hopefully some garage time at the weekend will allow me to try some more.

Ive already learnt loads and the video of a successful 2mm cut is encouragement.

If I’m being overly optimistic on my machines capacity maybe I need to rethink my longer term plan, but for now it’s the only CNC I’ve got.

Dave