Tool post Grinder Spindles

[Stephen OsborneParticipant @stephenosborne30223]

I am in the process of designing a toolpost grinder for use on my Colchester Student. I would like the spindle to run in Angular Contact bearings but being new to this subject, cannot find much information on the spindle design. I would appreciate any help in the form of plans, diagrams etc especially with the siting of the bearings, fits & tolerances and pre-load.

Many thanks in advance

[Chris CrewParticipant @chriscrew66644]

There is a book in the Workshop Practice series specifically on ‘Spindles’. I have not read it but it may contain the information you need.

[Clive Brown 1Participant @clivebrown1]

The “Quorn” T&C grinder spindle uses spring loaded angular contact bearings. It is fully described in both the ME magazine and the construction book by Prof Chaddock, who acknowledges it being based on Hoffman / RHP design recommendations.

[DC31kParticipant @dc31k]

Please do not take this the wrong way, but to me, your question is of the “can you please do my homework for me?” type. If you were to present it as “I have done the following research on my homework topic and discovered these resources. My outstanding questions are…”, you might reach your goal a lot sooner.

What prior art in the field of Model Engineering have you studied? The Quorn has been mentioned above; there are other cutter grinders within this hobby such as the Kennett, Stent and Bonelle.

What prior art in the toolpost grinder field have you studied? There is the ‘Little Giant’ toolpost grinder, the DuMore model, the Dynamic (Hemingway) and Duplex.

The technical libraries of the various bearing manufacturers would be a good place to start (e.g. https://www.skf.com/uk/industries/machine-tools/products-and-services/bearing-solutions)

https://dynospindles.com/vault/technical/Book-of-Spindles-Part-1.pdf

https://dynospindles.com/vault/technical/Book-of-Spindles-Part-2.pdf

[peak4Participant @peak4]

A longish video; I can’t remember all the content, as I was a tad off colour with Covid when I watched it, but certainly very informative.

 

Bill

[DiogenesParticipant @diogenes]

Harprit Sandhu’s ‘Spindles’ is good place to start, there’s discussion of the choices confronting the builder of a spindle, some pointers on ‘method’, as well as ‘words and music’ for a number of designs that can be built as presented or used as a basis for something incorporating your own ideas.

https://www.arceurotrade.co.uk/Catalogue/Books/Spindles-WPS27

It’s clearly not the Treatise on the subject, but you will know more after you’ve read it than you did before, and in any case £7.21 won’t break the bank (and I daresay is a bit cheaper than the Quorn paperwork.).

Talking of ‘words & music’ I’m pretty sure that Lawrence Sparey published a drawing for a toolpost grinder in his ‘The Amateurs Lathe’, but IIRC it’s presented at a small scale and I think the ‘how to’ is very limited – however if you’ve already read Sandhu, you’ll be better placed to figure it out, and it’s a good design.

[John PurdyParticipant @johnpurdy78347]

Stephen

There is an article on building a spindle using pre-loaded bearings in ME #3923 19 Jun ’92 et al. I’ve sent you a PM.

John

[Stephen Osborne]

On 5 March 2024 at 11:08 Stephen Osborne Said:

I would appreciate any help in the form of plans, diagrams etc especially with the siting of the bearings, fits & tolerances and pre-load.

There is an excellent SKF publication that goes into detail about these things:

Link

(Especially P57 et seq.)

 

[Diogenes]

On Diogenes Said:

Harprit Sandhu’s ‘Spindles’ is good place to start…

 

It’s clearly not the Treatise on the subject…

Indeed it isnt! I’ve criticised his designs in several previous threads (and others have agreed). The double taper roller bearing design is OK, but the others have design blunders around the axial location of the bearings and/or provision of adjustable pre-load.

Spindle design has been discussed here a few times (I don’t know how easy it is to search for threads with the new forum software…), and, as has been mentioned, the bearing manufacturers offer a lot of relevant information.

 

[Stephen OsborneParticipant @stephenosborne30223]

Gentlemen

Many thanks for your very helpful replies, I am sure I will find what i am looking for.

Incidentally, is it just me who finds the Forum Search facility ‘sub optimal’?

And, I promise to hand my homework in on time in future!

Cheers

Steve

[Kiwi Bloke]

On Kiwi Bloke Said:

I’ve criticised his designs in several previous threads…

But on what basis are your concerns raised? Given the narrow requirements and low duty cycle of a hobby toolpost grinder, what is a an economic, easy-to manufacture solution that is adequate for the task? How much material are you likely to remove and at what rate will you remove it at any one time? How many hours a month are you likely to use it?

If someone criticises my Smart car because it cannot gross 44t carrying 12m long reinforcing bars, they are mis-understanding the situation.

A couple of other toolpost grinders for ideas:

https://littlemachineshop.com/products/product_view.php?ProductID=2001

EMCO SOD toolpost grinder:

EMCO TOOLPOST GRINDER

(exploded diagram of the EMCO one is in the pdf manual)

[John PurdyParticipant @johnpurdy78347]

On the subject of spindles there is some good info if you go to https://www.schnorr.com and click on their “Downloads” “Literature” and download their “Design Handbook”. There is a lot of good useful info on using Belleville (Disk) springs to pre-load bearings.

John

[bernard towersParticipant @bernardtowers37738]

I think using disc springs is a bit specialised as they are bolted into a housing with no adjustment with all the preloads worked out before hand.(Ford differentials) Perhaps the simplest thing would be to use angular contact or magneto bearings with a fine threaded shaft for fine adjustment, especially if you go down to 40 tpi or more.

[David George 1Participant @davidgeorge1]

I wanted a grinding spindle for grinding the jaws on chuck which was well out of true and could be used for engraving as well and found that I could buy a high speed spindle which will do what I needed for a lot less than making one from scratch. It was easy to use the bracket which comes with the spindle and also made a bracket to fit the spindle to my mill.

there is a video of grinding the chuck here      https://youtu.be/2VKR45MYVEwre.

david

 

 

 

 

 

[bernard towers]

On bernard towers Said:

I think using disc springs is a bit specialised as they are bolted into a housing with no adjustment with all the preloads worked out before hand.(Ford differentials) Perhaps the simplest thing would be to use angular contact or magneto bearings with a fine threaded shaft for fine adjustment, especially if you go down to 40 tpi or more.

They don’t have to be, you can have a fine thread adjuster, or even measure what you’ve made and use shims

[David George 1]

On David George 1 Said:

I wanted a grinding spindle for grinding the jaws on chuck which was well out of true and could be used for engraving as well and found that I could buy a high speed spindle which will do what I needed for a lot less than making one from scratch.

I’m pleased that you’re happy with it, and very pleased to see that you have fitted an earth lead in the video – the power supplies that come with these spindles aren’t isolated from the mains.

Those spindles are just glorified motors though, running on ‘skateboard’ bearings in rubber cups, with wave washer preload. They aren’t very rigid at all.

I know because I struggled with one and tried to improve it. I eventually gave up and built a separate spindle, using the ‘ebay special’ as a drive motor:

(Some background here and here )

 

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