|Nicholas Hill||29/06/2019 21:33:57|
|25 forum posts|
As part of my replacing top slide project, see other post, I have had my Rodney Milling Attachment running today.
After running a DTI on the milling chuck, it became obvious it had a 0.002" vibration going on, with a elliptical path.
After much investigation, I concluded that pulley drive was the culprit. It seems the plate and the locating teeth, are of a very loose fit. I can see the 0.002" movement at the chuck, by just moving the top of the spindle.
What is odd, is that there appears little wear, as though the loose fit is intended.
My intention is to make a replacement plate, of a closer fit to the shaft and make some replacement locating teeth. Not a big job at all, but it doesn't "feel" right. Rodneys have known rigidity issues, so to have a loose fit on main drive, at the end of a cantilever, seems asking for problems.
Has anyone else had any experience with this sort of issue?
Drive system - the plate is screwed on top of a pulley, so the milling quill can move up and down, and be driven. PS it is upside down...
Underside of plate, with the locating teeth. Oddly no adjusting movement, the screws only hold it in one location.
Any with any Rodney experience, please comment. I'm still learning traditional British Engineering, but the Rodney seems to have several odd design ideas. Any hints on how to attach it to the bed, without three hands, and a fear of bed damage? Anyway of ensuring it is located correctly? Due to its size and shape, set square access is not easy.
Or does anyone know of where I can get a Rodney parts list / manual?
|Howard Lewis||30/06/2019 08:50:08|
|2341 forum posts|
1 ) Your problem stems from the shaft / bush not being a close enough fit.
You need to investigate the fit between shaft and its bearings, at upper and lower ends, not the driving keys!
Bore out the plate and fit a custom make close fitting bush. (May need doing at both top and bottom? ) Phosphor Bronze or Brass would be suitable materials for the new bush. Retain with and anaerobic such as Loctite, or with a flange and small screws.
Any chance of making the new bush (es ) longer, until travel is not quite reduced? This should improve location, and reduce wear in the longer term.
Is there wear because of a lack of lubrication? As part of the new close fitting (possibly longer ) lower bush could you incorporate a lip type oil seal, to prevent / minimise leakage? The shaft needs to be a good finish. A scored shaft will wreck a bush as you start up. Lightly lubricate the shaft where the seal will run, before installation. The seal should be protected from any sharp edge on the shaft during the assembly process by wrapping masking tape or plastic insulating tape over the edge at the end, before entering it through the lip seal. Once the seal and bush are in place, the tape can be removed.
Worst Case Scenario.
The Shaft is worn as well as the bearings. If so, you may need to think about skimming the shaft to clean it up, finishing with a polish with fine emery, followed by making new custom bushes, as above. M
Make sure that you remove all traces of the abrasive dust.
2 ) The keys only provide the drive to the shaft, NOT location, so do not need to be a particularly close fit.
Although, if you are really that keen, you could make two new stepped keys with the end that locates in the shaft a close fit, with the outer ends just a bit narrower, to be a close fit in the driving plate. Personally, I am not sure that any benefit would be worth the effort
If you are in any way not sure about this, find someone near you who has the experience to do the job with you. Joining a local Model Engineering Club would be a good start.
Where are you located?
Edited By Howard Lewis on 30/06/2019 08:52:37
|Andrew Tinsley||30/06/2019 11:13:45|
|919 forum posts|
I have the ML10 version of the Rodney miller. I think Howard has just about covered most things. I am not sure about the "Known defects" Of the Rodney. I use it for small work and find it to be in the same league as any other small mill. Basically take small cuts as it and other small mills are not exactly the most rigid of machines.
As for mounting it on the lathe, I have never given it a second thought. Although I suppose it I smaller and lighter than the ML7 version.
|Nicholas Hill||30/06/2019 14:33:12|
|25 forum posts|
Many thanks for the rapid replies. I shall read and digest Howard's reply. My first thoughts are, that I agree with the statement that the keys are not crucial to location, and the bore of the plate is more so. I can find little play at the nose end, so believe the lower bearing to be ok.
I also like the idea of joining a Model Engineering Club. I live in Beeston, in Notts, so I am sure something must be around me. It is the home of Myford after all....
Regarding my thoughts on known defects on the Rodney, there appears to be no way of ensuring it is located correctly, or anyway of adjusting for wear.
The whole alignment of the milling shaft is dictated by two hollow pins, if the alignment is out by a couple of thou, the whole thing seizes up.
As there is no bracing for the upper part, the whole rigidity is compromised.
As for attaching it to the bed, it is the lack of access that is the problem. To attach the rear foot, one has to lean the machine forward, with one hand, and try and locate a blind bolt with the other. The only way I could do this, was to rest the mill at an angle, on its spindle (quill?...I am new to Mills), on a block, while using my hands to locate and attach a nut to the bolt. But if the spindle suddenly retracts, there is a high risk of bed damage.
Overall it almost appears if the Rodney was built cheaply, and sold expensively - hence the compromises on rigidity, and accessibility. So I guess my thoughts were, that over 40 years, I assume people with vastly more knowledge than me would have found solutions to work around these compromises. The lack of a Rodney manual does not help!
Anyway, many thanks for the help and ideas.
|Nick Clarke 3||30/06/2019 19:30:12|
392 forum posts
Nottingham SMEE are in Ruddington and Erewash Valley are in Borrowash - both are quite close and there may be others.
|Nicholas Hill||01/07/2019 12:48:58|
|25 forum posts|
Yes, I've just contacted the Notts SMEE. I was slightly concerned by the railway focus of Model Engineering clubs. My work mainly involves high carbon steels. So shall wait for a reply, and go from there.
I've also been pondering on how to cure some of the Rodney issues. Conveniently the machine has a ground bed on the face of the vertical support pillar that contains the angle drive. So an angle plate could easily be fitted, which would brace the cantilever. It may require some damping with rubber grommets as one wouldn't want to induce vibrations from the drive shaft.
I will also investigate bushing - I am not sure there is enough wall thickness to do so? But that seems the most logical idea.
I am still not sure on the alignment issue - it has to be aligned in 3 axis, with nothing to guide! Until one discovers the optimum set-up, it is blind guessing.
Link to Rodney page on Lathes:
Thanks again for all the advice,
|Michael Gilligan||01/07/2019 13:13:40|
14024 forum posts
I regret to say it, but: That seems a very valid appraisal.
I look forward to seeing what 'silk purse' you can make of it.
|4723 forum posts|
Nicholas could be on a sticky wicket from the outset. Milling on a lathe is well known to be unsatisfactory compared to a proper milling machine. Partly lack of space for work, mainly lack of rigidity. The Rodney units may be a step up from a simple milling vice mounted on the saddle, but they still have a narrow base clamped to a bendy lathe bed. It's possible the weight and rigidity is less than ideal because the unit is a removable accessory.
Similar criticisms apply to Combination Lathe/Mills. Better than not having a mill at all due to lack of space, they are nonetheless distinctly less satisfactory than a dedicated mill. Milling on a lathe requires a delicate touch.
A worn out Rodney would amplify the effects of poor rigidity, but even in perfect order they are a compromise. Few would choose to mill on a lathe today. Milling is much easier on a milling machine, and they are not as difficult to own as they were when the Rodney was popular!
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