Cylindrical Grinder Internal Attachment

I've finally got the internal grinding attachment for my cylindrical grinder running. However, I have a couple of queries.

1. How tight should the belt be? I've tightened it enough so that it doesn't slip on start up. The Myford manual is singularly unhelpful; it just says adjust the motor mounts to set the correct belt tension, doooh. The top of the belt in the picture has a total play of about 1". When the spindle is running the top of the belt vibrates about 1/4".

2. After a minute or two of running the spindle gets warm. I can hold my hand on it, without too much problem, so probably about 50ºC. After a five minute run it doesn't seem to have got any warmer. I assume this is probably normal? I estimate that the spindle is doing about 20000rpm, and is lubricated and sealed for life.

Picture of the setup:

Regards,

Andrew

Belt play should be about a half inch otherwise it flaps about, the bearings heating up seems to about the same as my lathe main bearings and it runs fine.

Clive

Hi Clive,

Thanks for the information. I've tightened up the belt so that the play is about 1/2". It still vibrates a little bit, but at this stage I'm disinclined to tighten it any more. I did a few more runs, and got the impression that the spindle didn't get quite so warm. Given that the spindle is sealed and lubricated for life I guess the lubricant is grease. The spindle hasn't run for at least 5 years, so I assume that the grease needs to be re-distributed around the bearings. That's why I've been giving the spindle short runs.

I've got a selection of small grinding wheels on order; when I get them I'll have my first go at internal grinding.

Regards,

Andrew

I've now got my internal grinding wheels and have had a go at internal grinding. This is the set up:

The wheel is a 60 grit regular aluminium oxide, specfied for soft steels. The test piece is EN1A from the scrap bin. Grinding was done dry.

First off I tried grinding by moving the wheel radially out, and then engaging with the hole. This resulted in a hole with a good finish at the back and awful at the front. I assume this is due to the wheel and quill flexing slightly as the wheel enters the work? I then tried grinding with the wheel starting inside the job and then moving outwards radially until it started grinding. I then oscillated the wheel back and forth, but without disengaging from the work, a bit like honing. This seemed to give a more uniform finish. Like this:

The finish looks, and feels, pretty smooth. It measures anything from 0.7µm to 1.6µm Ra. I reckon the 0.7 is about right for the grit size but the 1.6 is rather disappointing. I never quite achieved sparkout, despite many passes.

So, does anyone have any hints on internal cylindrical grinding regarding techniques, methods, expected finishes or anything else?

Best Regards,

Andrew

Is there not supposed to be a cover or guard over that belt ? Don't have the belt too tight or you will preload the bearings causing wear, have you put any dressing on the belt to stop it slipping squealing ?

Thought just struck me.

How do you keep the grinding effluvia away from the lathe bed etc..with the almost tabbo of grinders vs machine tools ( NOT EVEN IN SAME ROOM !)..

Seriously, the two don't mix well. so whats the solution ( tool post grinder seems good alternative to T&C machine ..) Good extraction? way covers?..

TIA

Ronan: Yes there should be a belt guard. I have a Myford original cast aluminium belt guard for external cylindrical grinding but nothing for the internal. It's on the list of things to make. I don't think that the internal grinding setup was original to the machine, as I had to bore out the drive pulley to get it to fit the motor shaft. How tight is too tight for the belt? Following Clive's advice there is about ±1/2" play on the belt. The belt doesn't slip on start up, so I haven't added any dressing.

Jason: Errr, not sure I follow the comment about lathe beds? My lathe is in the same room, but it's about 12 feet away. The grinder does have full flood coolant, it's just that the nozzle is fixed for external grinding, and isn't adjustable for internal grinding. I have a plan to throw the whole thing away and fit a LocLine arrangement so that I can have coolant for both external and internal grinding. I need to make a bigger splash guard too.

MIchael: Thanks for the link. As a first off I'm quite pleased with the finish, but I'm sure my technique can be improved, which is why I'm looking for any hints.

Best Regards,

Andrew

Andrew.. sorry thought it was attachment to lathe..

Futher reading of the suggested link gives a more balanced concept of the "horrors" of grinding on a lathe..

if it was not for the abrasive problem using a toolpost ( live tooling) grinder might be useful to me ..cutter /work holding check / .indexing on lathe spindle check.. / feed and angle advance check ./

. just to me seemed half way at least to a T & C grinder...

Now what about bonded diamond as apposed to grinding wheels ?..

regards

Would anyone know where to get a internal grinding spindle for an early Myford cylindrical grinder, like the blue attachment shown in Andrews post.

I've been looking for one at a reasonable price for quite a while and haven't found one, so any help locating one would be very much appreciated.

Regards

Ian

Ian,

Sadly I suspect you'd be better off searching for the Holy Grail. There is a Myford internal grinding spindle on Ebay, but it's in the US and is $1500. Have you talked to Jubilee Machine Tools in Derby? They're not cheap, but they do know about grinders, and Myford in particular. At least they'll be able to give you a view of the market.

Regards,

Andrew

Andrew thanks for the reply, I've seen the one on Ebay and that is almost twice as much as I paid for my grinder.

Since I'm in New Zealand they are rarer than the Moa, I would have thought there would be a few hiding away in the UK and it would just be a matter of flushing one out. Perhaps I'm wrong.

Regards

Ian

Andrew,

With regards information on cylindrical grinding you might want to get a copy of Nortons book The A-B-C of Internal Grinding another one to get would be The A-B-C of O.D Grinding.

I have both books and have found they are a great reference.

Regards

Ian

Hi Ian,

Thanks for the info on the books. I was vaguely aware that Norton had published some books, but it sounds like I need to be rather more active in searching out copies.

As far as the internal attachment goes, I suspect part of the problem is that they tend to get sold along with the grinder, which is how I got mine, rather than separately. If all else fails it shouldn't be beyond the wit of man to make a spindle. All it needs is a couple of angular contact bearings and a spring preload arrangement in a sleeve. I'm in the process of planning something similar for my surface grinder, where I've reached the tentative conclusion that the bearings are badgered.

Regards,

Andrew

Hi Andrew,

I use Bookfinder.com to find a lot of books, I got the Norton Tool & Cutter grinding book recently, along with a couple of other books.

I have thought about making a spindle for doing ID grinding, I do have 3 stone mount arbors that fit in the spindle of the Myford ID grinding attachement (I think)

Recently I found and purchased a late model swivelling workhead for a Myford cylindrical grinder, I imported it from the US and it cost less than NZ$600 landed here.

Regards

Ian

Edited By Ian Owen on 01/10/2012 06:57:48

Ian, TopmaQ tools used to have a tool post grinder, have not been in their Christchurch shop for well over 2 years, they moved fron mid city a good bit before things got all shook up, I know , most their stuff is Chinese r*****h. Ian S C

Hi Ian,

I've put Norton grinding books on my whiteboard, so that'll remind me to do a search for them every so often. Your swivel workhead looks great, like new condition. Does yours use odd belt lengths? Mine seems to require at least one of 17.6" length, which is unobtanium. I'm using 17.5" instead.

I think there are two types of quill for internal grinding. One for the add-on unit like mine and a different one for the later swing down unit. I believe that the swing down units also used collets for use with mounted points. I only have one quill with my internal attachment. However, when I need different sizes it shouldn't be difficult to make some more.

Regards,

Andrew

Hi Andrew,

Since my grinder is an early one I am looking for the quill for internal grinding which bolts on the front like yours.

Here goes a pic of my Myford

And what I think are the internal grinding quills.

Which belts are you talking about?

The swivel work head has only got one belt to drive it. I got an adaptor and 3 jaw chuck for the swivel workhead from the US. Since the swivel workhead uses different adaptors and collets I needed at least one adaptor and chuck.

The myford when I got it came with one extra grinding wheel and hub a set of collets (imperial) and a set of centres but no chuck or backing plate.

As you can see from the pics it needs a bit of a clean and paint. I plan on converting it to run on single phase using an inverter (hopefully). I need to find out if the work head motor is AC or DC.

Regards

Ian

Hi Ian,

Here's a picture of my grinder, I run on 3-phase hence the red plug on the floor:

According to Myford my grinder was built in 1969; unusually I have the original manual for the machine. To the left of the machine is a small stand I welded up to hold the accessories. Here's a picture of some of the accessories that I sent to Myford to confirm what they were:

1. Swivelling workhead

2. Angled wheel dresser

3. Travelling steady

4. Internal grinding attachment

5. Internal quill and nut, which agrees with what you think are the internal grinding quills

I also got a faceplate, 4 jaw chuck, spare workhead noses, two wheel holders and a centre, but no collets. I believe that the newer machines used standard collets (4C?) but the older ones used non-standard collets. So far I haven't really missed not having any collets. Both my workheads have DC motors, but I think later models used AC motors. Looking at your picture I'd hazard a guess that your swivelling workhead has an AC motor. Finally here's a picture of the back of my swivelling workhead to illustrate the two belts, the loose one is supposed to be 17.6".

I need to move the motor position to adjust the tightness. Rather annoyingly the belt lengths are different again for the normal workhead.

Regards,

Andrew

Hi Andrew,

Your Myford looks a lot tidier than mine, and the accesories you got with yours I can only dream about.

I looked at my standard workhead today and all the belts look correctly tensioned, but neither have any markings on them. How do you date a Myford Grinder, the serial number on mine is S 58201.

The one thing I really really want is the internal grinding spindle. My grinder was sitting at a used machinery dealers for approx 3 years. I made him an offer after 2 years and he turned it down, I made another offer after 3 years (the offer was half my original offer) and he accepted it. I heard it run and everything was quiet and smooth.

Since I've used Inverters quite extensivly for running my 3 phase machinery I thought when I rebuild the grinder I'd change it to inverter control and replace the DC motor on the standard workhead with a AC motor.

Regards

Ian

Hi Ian,

I got Myford to date mine from their records. The machine number for my grinder is S.89561VTF. I assume that the numbers do not run in strict sequence; otherwise yours would be very old. From the picture I'd say yours was the same sort of vintage as mine. Although my grinder is a MG12, as opposed to the earlier MG10, it takes a 10" wheel. I think that later models took a 12" wheel.

I bought my grinder unseen off Ebay. I was rather ignorant about the accessories and just took them as they came. I collected it myself, about a 200 mile round trip. Even the lorries were overtaking me on the M25.

Regards,

Andrew