A cheap toolpost grinder

[bazmak]

I have been following Ghosties toolpost grinder thread with great interest
Workmanship and thread are top notch However as a famous happy fisherman
used to say Monkey see monkey do and it got me to thinking about making a cheap/free one.A few years ago i bought a box of assorted bits and bobs for $5
and while cleaning out one the cupboards found one of the items
A small/compact powerfull Hitatchi laminex trimmer.Looks ideal
520w,30,00 rpm and fitted with a 1/4" collet chuck.Tight bearings and obviosly little used.I remove the small plate,guide and stop etc and trimmed a couple of fins off the body.Made a mounting plate for the lathe,a couple of aluminium
plates and puchased a s/s jubilee clip for $2.5
Photos tell the story.Cheap and simple.Will source some small grinding wheels
and find some thing to do with it. Watch this space

 

[goldstar31]

I'm intrigued and offer two of my thoughts about uses.

The first stems from the fact that MOST tool and cutter grinders available to the hobbyist will not refurbish dies. Chaddock's 'Quorn ' will --if one makes a bloody big wooden pulley and gets the 6000rpm up to 14000. The rest- perhaps- are rather more challenging to covert. Yes, I did read the 'expert's' who had never done it- pronounce. You have exactly the tool to do that job.

The other was more recent. It was a local guy that had strapped an angle grinder onto a a Myford S7B.s vertical slide and used it to cut slots on work held in the lathe spindle chuck. He'd made a couple for E-Bay and I was tempted but later found the vertical slide was not part of the deal. So slot cutting is possible with a 'router'. In the same sort of context, the router with a - say 1/8th (3mm).slot drill will 'do' the spiral column of an 1" TPI for the Quorn. This, of course, prompts the fact that that Dennis Chaddock made his own 1/10th milling cutters to make his - was it a RR Merlin engine?

Being a simpler sort of soul, I got to that wonderful problem of how George Thomas ground a 140 degree vee on the top of his rear parting tool so that it narrows the little rolls of swarf. when it is used upside down. I built the thing in the days of Yore but used a well worn disk to grind a curve instead of a vee in my version of his excellent design.


And there, Baz, you have my 'Moonbeams from my lesser lunacy' So I hope that they have proved useful.

Norm

 

[Blogwitch]

Baz,

That motor should be perfect for a toolpost grinder.

Where people go wrong is that they use motors that are too slow. It is very easy to gear down to give slower speeds, but rather more difficult to speed up to the required speed without overloading the motor.

My TG had a burnt out motor when it was given to me, but through a friend I got a motor that was just a little faster than the original, it was dead easy to make a pair of crown pullies using the original flat belts to get it to the same spindle speeds as the original.

External grinding ins't too critical on speed, but some of the tiny internal mounted points do need that high speed to work correctly.


John

 

[Brian Rupnow]

I'll be watching.---Brian

 

[velocette]

Hi Bazmak
Small grinder tips to fit at "Supercheap" you can profile them to shape with a carbide tip or a diamond dresser.

Eric

 

[bazmak]

Thanks for your comments all. After sleeping on it overnight i had reservations
that the the speed of 30,000 rpm would be too fast.However i only have in mind to use the small cheap stone wheels or diamond, like a dremel on viagra
No specific use at the moment but will try to improve the chucks by
touching up the jaws lightly.Just as a trial.Will keep you informed

 

[goldstar31]

I'm wondering why 'there is needs to be vibration' considering that a present day hand held dental handpiece can rev up to 800,000 rpm. OK, 400,000 is the sort of norm for the average clinician.

There has been a lot of talk about bearings and whatever but the Quorn home built cartridge is capable of 14,000 rpm whilst the ones on the Stent and the Kennet are- well- not to be trusted beyond say 6000. Yes, I have all three!!!

Another thing that leaves me in some doubt as I can better the finish obtained at 6000rpm from some of my brazed carbide tooling compared to decent quality CCMT tooling. I'm not talking about somewhat possibly inferior stuff from a backstreet in HongKong.



Perhaps someone will enlighten me, please?

N

 

[DJP]

Has there been any consideration of using an air powered die grinder for this application? They are small and fast to suit small stones. Air consumption can be high when continuous running but they power up quickly so running it only during the cutting phase should be possible. I don't recall bearing failure ever being an issue with these tools as they are intended for industrial use. Noise will be high but that's why hearing protection, goggles and a mask would be necessary.

Just a thought for the conversation.

 

[BucksMachinist]

Great mod !

 

[BillH]

Why not a brushless r/c airplane motor? 30,000 rpm is easy

 

[bazmak]

Lots of ways to do this from Ghosties professional model thru air grinders
and routers etc to dremels,all have pros and cons.I just happened to use what i had in the drawer.I personally think that 30000 revs is too fast,but if the the bearings are good then it should work and it cost me nothing

 

[goldstar31]

I had a woodwork job, went out and bought a router and 'read the instructions' to find that it had been a tool post grinder.

Another day, my wife brought me a pitman driven and redundant dental drill from one of her surgeries. Sadly, she's no longer with us.

Perhaps the best of the trophies is her orthodontic kit with lots of wire bending kit. My wife found a use for the gold fillings which she had extracted! She melted them down and centrifugally cast them into a little ingot to wear.

So, Baz, I'm with you in your comments
N

 

[bazmak]

Will resurrect this thread as i have finally used the toolpost grinder and it works well
On my thread restoration of a Myford lathe,i fitted thrust brgs to the leadscrew
The leadscrew is 7/16" or 11.1mm so i ordered a couple of described 11mm thrust brgs
They were actually 10mm with the 2 halves being 10mm and 11mm so i used the 2 11mm halves
to one side of the LS brkt and fitted a 12mm thrust race to the other side.With Myford 2 i used
2 no 12mm thrust brgs but at 26mm od and 9mm wide they were almost too large.The 10mm
ones at 24od and 8 wide were more suitable so i ordered a pack of 10mm.The bores measured
at 10.7 to 10. 8mm dia so i set up the toolpost grinder and enlarged the bores to a couple of thou
over 7/16ths.As i am making new housings i can locate on the od and machine to a nice pusf fit
on one half and opened up a couple of thou on the other half.Works great and much more compact
when fitted to the lathe

 

[goldstar31]

It's nice to see some restoration work to improve an old lathe.
I'm sort of betwixt and between as I have been offered a rather nice very much more modern( and easier to use) Myford Super7 with a gearbox and a powered crosslide .

Digressing somewhat, I have fitted a new Fagor rotary DRO to the SiegC4's topside.
Actually, I was quoted for one unit but TWO arrived complete with new feed screws and nuts------all for a modest £50.
On the Myford issue, I noted that someone had raised the question/suggestion of a milling spindle as part of an alternative to getting a mill. I still have two or one milling spindle and the other is a drilling/grinding one. Both out of G.P.Potts design and construction. The question remains of how to power the 'beasts'

I had a daft notion having replaced a virtually wrecked petrol grass strimmer where spares are like rocking horse manure. Of course the motor is fine- but the rest is kaput. It COULD drive the auxiliary gear.

Continuing, I bought a replacement Chinese 4 in one machine for a mere £160 and seriously wonder how something was so cheap because it not only strims my lawn edges but has a chain saw, a hedge trimmer and a gadget to top my high hedges. Oh, and a blade to attack the ground ivy

And I think that it is all relevant being a petroil machine of 32cc 's- all laughing and scratching and other people are buying plans- or not buying plans and buying or not buying castings and then having to machine---- or have I lost the plot?

Sorry Barry but I DID get carried away

Regards

N

 

[goldstar31]

A million years ago, I played about with 'grinding things' Amongst them , I actually earned pennies( not much more ) with grinding things- like rubber and carbides and so forth. The question is whether 'we' would grind sintered bronze bearings.

Perhaps someone else might care to add something.

Quizzically

N

 

[Anatol]

Interesting discussion. There was mention of air die grinder. I have a nice Makita die grinder, 1/4 shaft, relatively small - very tough. Basically any motor with roughly the right revs and torque should work, with a chuck mounted on it?

 

[goldstar31]

One of the best and cheapest is from the Quorn plans and this is a 1" diameter 'cartridge' which will run to 14000 rpm.

Design comes from RPM or Rank Pollard or whatever but 'boy, does it go'

Dennis Chaddock used it to make 1/10th diameter milling cutters on his homemade Dore Westbury mill which made his Vee Twin.

Very topical today
N

Actually, there is a set of 1" diameter 'cartridges'
One is Professor Chaddock's
whilst the second is from the much simpler Kennet design and the other is from the Stent which is a diminutive Clarkson grinder.

I also have a Potts but this has plain bearings. Possibly, the Potts was the 'standard' tool on the much despised(now) vertical slide. And almost everyone is actually copying direct or modified engine plans based on the use of one of these

 

[MRA]

Looks good, Bazmak. I recently rescued (of all things) a vibrating poker machine used for making poured concrete flow and getting the air out of it, from a skip at work. It's like a fast (12,000 rpm?) motor with a really *heavy* duty speedo cable attached to it, with the vibrating poker dongle thing (containing an eccentric, I presume) on the end. It came with 2 cable outers and about 10 springy inners, and a couple of dongles. I hope to take the eccentric out and use the dongle outer case as the bearing housing to support an ER25 collet chuck, since I have a bunch of things using these.

 

[Nick Hulme]

One of the best and cheapest is from the Quorn plans and this is a 1" diameter 'cartridge' which will run to 14000 rpm.

My home brewed belt drive ER11 milling spindle runs very sweetly at 28800rpm to 30000rpm on a pair of fixed nose ball races and a floating pulley end ball race, I based it on some of the basic concepts from Harprit Sandhu's book on building spindles.

 

[russgl]

Interesting discussion. There was mention of air die grinder. I have a nice Makita die grinder, 1/4 shaft, relatively small - very tough. Basically any motor with roughly the right revs and torque should work, with a chuck mounted on it?

I made an adaptor from aluminum and fitted in a makita 1/4" die grinder, works well with substantially more power than an air grinder, runout on shaft was low, too.
Put the adaptor with the grinder on a QCTP and it was still very ridgid.