Grinding spindle.

[Alec]

Hullo, I looking for ideas really. I retired from precision engineering, college workshop technician and 30 years in a shipyard and now have a small Colchester student and similar size vertical mill. I have been making the Quorn t/c grinding machine, which has been a challenge but enjoyable.Being me I am looking to remake the grinding spindle with a different design, perhaps angular contact bearings , just because I can, nothing wrong with the original design by the way. I'd welcome ideas on this please.

 

[goldstar31]

My Mark1 Quorn has the spindle as per the Chaddock design and works fine. I also hsve a similar one on my Stent for whivh plsns are availsble in the IK from Blackgates Engineering whilst I have a Kennet but I doubt that few of us will have drawings. These also work fine.
I have a Potts pair of drilling and grinding spindles and one is like rocking horse manure whilst the other is as scarce as hen's teeth,
Now I have the kit and drawings for the Mark3 Quorn and the drawings and instructions are availsable from Hemningwaykits for £65 and postage etc.
In addition there is a MAP book in the Workshop seriesavailable entitled Spimdles by Harprit Sandhu

I recently purchased a Potts Vertical mullung tool etc made to a high standard. Again, these are old and a bit like hen's teeth but there is an interesting conversion of one to have a spindle. Maybe Googling Lathes Co UK. There is( somewhere) a a film of of it and the conversion.

Agin, I suspect that BaronJ(here) has created his own spimdle for his Derek Brooks-type tool and cutter grinder.

I hope that this helps

Norman

 

[timo_gross]

Hello,

here you will find some smaller spindles under the label "Spindle / internal grinding arbor chuck",
if you go a little into the details you will find some cross section drawings, maybe gives you some idea.

https://en.matchling-tooling.com/
Unfortunately I do not know how much they charge for the spindles. I am quite sure it is not cheap.

Greetings Timo

 

[SmithDoor]

Welcome to group.

You find today most tool post grinders use ball bearings.
I would look at 6203 seal bearings it is lowest cost ball bearing.

Dave

Hullo, I looking for ideas really. I retired from precision engineering, college workshop technician and 30 years in a shipyard and now have a small Colchester student and similar size vertical mill. I have been making the Quorn t/c grinding machine, which has been a challenge but enjoyable.Being me I am looking to remake the grinding spindle with a different design, perhaps angular contact bearings , just because I can, nothing wrong with the original design by the way. I'd welcome ideas on this please.

 

[goldstar31]

The spindle cartridges for the Mak1 Quorn, the Stent and the Kennet ---ALL are only. 1" in diameter and the 'motive power' rennended for all of the 2880Rpm 1/6th HP AC.

However, it would aappesr that the OP has already 'done' the Mk1 spimdle satisfactorily and is capable of making an alternative unit.
Rge Potts bearings are 'plain' ones and are capable of high speed duties.

I haven't looked at ALL the 33 pages of the Mk3. I'm making the alignment tools which were not detailed. when I made my Mark1

 

[petertha]

Tuning in. Not directly related but some discussion I initiated on toolpost grinders.
https://www.homemodelenginemachinist.com/threads/toolpost-or-other-grinding-in-the-lathe.32543/I know the likes of Themac & Dumore use angular contact bearings, but others went about it with other arrangements. I've read some discussion on Themac Ebay rebuilds where people didn't get the adjustment just right or used the wrong kind of oil & ended up adverse running issues, usually heat but also play or vibration. And usually the vendor cost to repair approached a new spindle so always made me apprehensive about bidding on a used one, especially if it looked like it was well used. Could it make a shiny surface? Probably. Could it reliably hold tolerance grinding a shaft to say a typical bearing fit? That's another question.

I bought this book a while back.
https://www.amazon.ca/Spindles-Harprit-Sandhu/dp/1854861492While it lays out several generic designs you can adapt to your own dimensions & bearing availability and the designs are deemed 'useful' for model engineering, it doesn't really provide any numerical data in terms of runout, max rpm, load comparison, heat/lubrication... IMO just looking across all the designs its pretty much the same work to produce the stepped shaft, spindle case & end caps so why not go with the best bearings the budget allows... whatever best means.

I'd like to see your Quorn build pics. Maybe there was some mention of bearing How's & Why's in the documentation? Look forward to what you settle on. I find this subject to be another grey area.

 

[goldstar31]

Having built a Mark1 so many years ago, there is a lot of old wives tales usually from old wives who know less than npothing about Quorns and probably not much more about other topics,
There is no 'grey' area.
Without question, most. will agree that it is a challenge.
Now in my 91st year, I'm challenging myself to make another one but a Mark3 which is, perhaps, slightly less difficult.

I'm looking forward to re-sharpening my one remaining hacksaw blade

 

[petertha]

Alec, not sure if you have seen this site but he did a pretty detailed documentation of his Quorn build & lots of reference material.
https://thebloughs.net/metalworking/quorn-tool-and-cutter-grinder/#logsHe discusses alternate bearings just a bit in The Spindle chapter
https://thebloughs.net/quorn-parts-401404-the-quill-body-caps/

 

[Charles Lamont]

You find today most tool post grinders use ball bearings.
I would look at 6203 seal bearings it is lowest cost ball bearing.

The things that are called 'spindle bearings' for a reason, are angular contact bearings.

When investing a lot of time in making something as good as one is able, lowest cost is not likey to be the prime criterion.

I have not started building my Quorn yet. The castings have been seasoning for over 15 years. But I have designed a spindle cartridge that is 36mm diameter and uses 30 x 17 x 7 angular contacts, variously designated 71903 or similar, which can be had as precision spindle bearings or 'bicycle' grade (but nothing in between).

I could not fit a preload spring cage in to the annular space available round the beefed up spindle, and had to settle for a wave washer for preload. I still don't know if I will make it standard or fancy, or both.

 

[goldstar31]

Greetings Charles. I have ticked your comments about your spindle cartridge but I have serious doubts about whether the castings will be 'desdoned'
I'm not an engineer or anything like that but friends and my family were.
Classiically, castings were rough machined and left outside to weather for a year.
George Thomas writing in his early Univwesal Ilar book. It preceded inclusion in 'Workshop Yechniques' described how the Mark1 arms 'nipped' after machining and somehing similar is mentioned by Chaddock in the Quorn book. I hit the same snag whwn boring the headstock of the the Westbury mill. drill( preceding the Dore estbury of Arnold Throp} The boring was spot on until I sawed the slot and it nipped and I spent hours handscrapimg it..
Again, I have a Kennet with a similar 1" bore to take a similar caertridge to the Quorn and it 'nips' and I crudely use a wide screwdriver blade as a wesge.
The 'new' Quorn mark 3 suggests split cottars- mine on my mark1 are not split.
So read Chaddock please and possibly spend an additional £65 on the purchase of the new plans and instructions. Thesee have several 'easier' suggestions from those on the Mark1.
The rotary table does look easier.
Apologies if I have made mistakes here as I suffer from Low Vision and Macular Degeneration in one eye and the other doesn't work.
I DO hope this helps your construction

Regards

Norman

 

[PeterDRG]

I'm doing the Broadley design, using Belleville washers, as I didn't fancy the pocket holes and spring consistency for the Quorn one. Im using the same design in my Stent and Tool Post grinder..

 

[VirginiaGuy]

Conventional ball bearings are not good at handling loads that are parallel to the shaft (axial loads).
Tapered roller bearings, often in pairs with the smaller ends closer, provide a way to handle
the axial loads parallel to the shaft.
They can be set up to allow for clearance when the bearing warm up and grow larger in height.
If the clearance is not enough, or taken care of in the bearing stack the bearing can quickly destroy themselves.
Many of these bearing stacks us flat spring washers to proved clearance over operating temperatures, while essentially maintaining zero functional clearance.clearance.
The spring washer compresses to hold the stack tight while allowing enough movement to prevent binding.

 

[Charles Lamont]

Norman, the 'seasoning' remark is a standard jocular excuse for not getting started. Because of problem with bores closing up when slit, I have already drawn up split cotter clamping (actually mostly one-sided) for most of the clamps. My copy of Chaddock's book is falling apart from use, and I do intend to get the Mk3 drawing set, even though I already have Mk2 castings.

 

[Alec]

The things that are called 'spindle bearings' for a reason, are angular contact bearings.

When investing a lot of time in making something as good as one is able, lowest cost is not likey to be the prime criterion.

I have not started building my Quorn yet. The castings have been seasoning for over 15 years. But I have designed a spindle cartridge that is 36mm diameter and uses 30 x 17 x 7 angular contacts, variously designated 71903 or similar, which can be had as precision spindle bearings or 'bicycle' grade (but nothing in between).

I could not fit a preload spring cage in to the annular space available round the beefed up spindle, and had to settle for a wave washer for preload. I still don't know if I will make it standard or fancy, or both.

Good morning, I am very interested in your method/design. I agree , investing time and all id use the best bearings I can get, and worry about the cost afterwards. So your 30 x 17 x 7 mm angular contact bearings are perfect, the Quorn mk3 uses 30 x 13 x 7 magneto bearings with a spring box to allow for heat, expansion etc.it uses a spacer to control the inner race and the springs do the rest, oh and the grinding end outer race is held by the end cap. Id like to see your drawing if possible.

 

[goldstar31]

FWIW I havw a note in the Marl3 Quorn schecules of parts thaat the bwaeings are noe Magneto b earings E13 as a replacenment to the Rank Hoffman Pollard ones supplied to the Mak1 and the old Kennet and I presume those fitted to the Blaxkgates rype Stent of fabricated parts.
What is interesting is that the successor to the Kennet used a motor holding the wheels directly bit thgis is the same motpr that replaces the Paravalux motors oribibally designed for ALL the models in the past.

So what comes with the Qiorn. Mk3 is EIGHT abrasive wheels to do the extra grindong tasks of which the Quorns are claomed as being aubable to perform

Then believe it or not, the kit supplier suggests that MORE collets are made to accept both diand and CBN whheels which ALL the varipous machines can adopt in addition( more chuckles)

And I need LIGHT or so the hospital invitations 'suggest' and a mate of mone who is an electrical engineer has re-wired my little workship with brighter LED lighting.

So next weel, I'm leaving all this to see some really massive grinding. I'm heading again the U shaped glaciated valleys of the Scottosh High;ands,with the rocjes moutonnee and the drumlins where the ice sheet stopped. There's new grit there as my wife's ashes are scattered there. Mine? in due course


Cheers

Norman

 

[petertha]

Can someone guide me through the basics of a 'typical' spindle? I'm having difficulty visualizing the forces that are on the system and exactly what the compensation device is trying to accomplish. Here is my guess, please tell me where I'm correct or misunderstanding.

For discussion purposes I grabbed a pic of Quorn (top) and Broadley (bottom). Despite likely differences in bearing choices & dimensions, they seem somewhat similar from across the room. What I think I'm seeing is: the collet side bearing is fully constrained (yellow arrows). The ID is constrained by the sleeve tube on one side & spindle on the other. The OD by the spindle case on one side & the threaded end cap on the other. The pulley side bearing looks constrained on the ID by the sleeve tube on one side and pulley/end cap on the other. The OD is being acted on by the spring force, red arrow, via wavy washers or springs etc.

So there is still some tiny amount of gap between the balls & either side of their respective bearing race. Is the spring/adjuster attempting to bring that within certain limits? How is that set & how do we know we have arrived at the right amount?

Now we introduce elevated temperature at running conditions. I assume the heat originates from the bearings and flows out from there? (red shade, 2nd sketch). So what exactly is thermally expanding relative to what? For example does the spindle shaft become hotter relative to outer housing, therefore grows more in length, therefore bearing races now out of alignment, hence the need for compensating spring force? If the bearings are the heat source, why wouldn't the outer housing see comparable temperature rise & expansion because they are mated to the bearing OD's & similar mass? Often spindles are oil filled so wouldn't that transfer heat uniformly?

I have more questions, but maybe lets start here in case I'm already off down the wrong path.

 

[petertha]

And this is how I quickly come to realize I don't even know what I don't know. The link Timo provided shows a spindle with double AC bearings on both ends & spacer tubes in between. Do the fixed & float force arrows look right?
https://en.matchling-tooling.com/upload/images/38013.jpg

 

[goldstar31]

My comments etc deleted as qustioner has now admitted to having information of which I have no interest.
I am regarding this as a hobby which is in full kee[ping with a HOME workshop

Norman

 

[petertha]

Some good (industrial strength) reading here Documentation - DynoSpindles
These 2 pdfs in particular

 

[retailer]

I built the Quorn a few years back (MKI I think) and built it to the original design - it has a spring box with 6 springs - these springs provide preload to the bearings, I recall that if you push hard enough on the pulley it will move against the spring pressure, of course when grinding the forces are the reverse of this - back against the pulley. Without looking at the book I can't recall how much force the springs provide but possibly around 5kg, I measured this with a set of kitchen scales - trial assembly - press down on the scales until spindle moves forward a few mm- read the weight/force off the scale, mine came out a little too high first off so I deepened the spring pockets by a mm or so, it wasn't hard.
The Quorn spindle is not hard to make (time consuming but not hard), the hardest part was the labyrinth dust seal, this type of seal is frictionless, I assume this is needed in preference to an oring or similar type seal where there is friction which would eventually cause heat buildup, I made an annular cutter which helped.
Chaddock intended it to be a precision grinding spindle - the final cuts are taken from the collet taper once the spindle is fully assembled - Chaddock states that once the final assembly is done the spindle should not be taken apart as it would not go together the same - I couldn't see this but I still followed his instructions to the letter. I cut down an old military rifle barrel for the main shaft, convenient as it was not only a high grade steel but already had a hole through the middle
I've run my spindle for for up to 2 hours or so at a time with both white grit and CBN wheels and it barely get warm, the motor gets much hotter.