Member postings for Chris TickTock

My Contribution after taking on board all posts and further research. (Any comments welcome)

Climb Milling:

Downward force is exerted on work so can pull out an end mill out. Backlash is potentially added to depth of cut. This is especially important in lighter machines and those without back lash elimination. In more robust / rigid machines with heavy iron tables and tight gibs may not be an issue.

In lighter machines though the back lash if poor can be dangerous e.g. if milling at an intended .005 inch and the machine is poor with .020 backlash then you may get 0.025 cut which could break the machine. So depth of cut plus back lash is key.

Finally climb milling is reputed to give a better surface finish. However there are opposing arguments as always one being that tool deflection can introduce some surface imperfection.

Final advice from my findings is at least be aware of the dangers of climb milling, something I was totally ignorant of before asking on this forum.

Chris

Yes having a second look they are both right for work movement

Chris

Would do if they were correct for cutter movement but I don't think they all are...correct me if i am wrong?

If the text that we cannot see states X axis is for cutter movement and the Y axis for work feed then fine, otherwise in error.

Chris

Edited By Chris TickTock on 24/09/2020 13:48:23

Edited By Chris TickTock on 24/09/2020 14:15:14

Thanks Jason, when struggling to first get this understood the arrows can be confusing. Here they show cutter movement which translates to stock feed with cutter still. It is easier to understand with arrows denoting the stock feed direction. Not a problem now i get it (hopefully).

So a quick summary, please put me right if I go wrong:

1. Lead screw mills should use conventional milling as table forced with each flute against back lash)

2. if only light cuts are to be made you could mill in either direction

3. No baring on plunge cuts (hole making and slots)

4. If heavy cuts are taken opposing forces cancel each other out. (why on earth would you take such a big cut, not on my Sherline I think/)

Chris

Good point Michael. My sketch wrongly has cutter force represented as a single force. In the sketch as is opposing forces cancel out trouble. However it is an interesting point if I went to widen the slot. I could cheat and just take light cuts of course which is probably all that is needed. If a larger increase is called for then if I was to use the same cutter, each side would need to be positioned accordingly.

Chris

Jason, OK I think I get most of this now, my error was not understanding that cutter direction matters only in relation to where it is milling on the stock (silly idiot).

Having said all that are there rule of thumbs for positioning the cutter on a certain side and moving the stock in a given direction?

Such as for taking a face cut off with cutter in front of stock at left front corner move stock to left for conventional milling?

Chris

Thanks Jason, will leave it as tired and have a look tomorrow with a fresh mind.

Chris

Sherline state conventional milling should be used for all hard materials and roughing but that for lighter finishing Climb milling can be used. I am still getting my head round all the permutations. OK I get that you can face stock moving it say left or right but what about end on on the Y axis if I were to mount the stock as in the diagram and feed as per arrow this is climb milling and a no no position then??

Chris

Edited By Chris TickTock on 23/09/2020 18:09:04

Hi Guys,

i am currently going through what I know or think I know with regard to using my Sherline mill to make a pinion cutter. I have found several factors that could have added minor errors such as using the mill ends inappropriately in terms of depth cut etc. However I have come across climb milling v conventional milling. It appears at first glance to be just the direction you move the end mill towards the stock.

Can anyone give a good simple explanation as to what I should know about climb milling and any likely implications when using the Sherline Mill.

I have no idea about how naive this question is so charity may be needed.

Regards

Chris

Had not yet heard of blackening steel so looked it up. Could be useful.

Thanks Neil and all for posting

Hi Guys,

Don't want to give the game away on my being tight but I have just taken receipt of a piece of oil hardening gauge plate (1/4 inch square). It is O1 so needs oil hardening. it will be about 2 inches long when made.

Anyone recommend a 'cheap' oil that will suffice for hardening this?

Regards

Chris

Many thanks Jason and others will chew over this tomorrow. I don't have DRO so iby hand tIwill introduce error I suspect. Truly wonderful video.

Chris

Posted by JasonB on 21/09/2020 18:18:32:

put up a drawing

Hope this helps. Remember this has to be fairly precise. As I said I would be minded to say put the 3mm dia end mill to the side of the stock, zero hand wheel, then raise the end mill move in the specific amount plunge cut and move forward to remove front remnant. Is this the wrong way to do this Jason/

Chris

Either way do as suggested in the other thread and drill a 1mm hole then file or mill back to half way.

Thanks Jason but although this is related to that thread this post is for a different purpose it is for milling in small radius in a cutter to improve accuracy of milling. Up to I would guess 4mm then moving the end mill out straight to leave parallel front edges during production stages. So in this case drilling a hole is not going to work on its own.

For example if I wish to put a 3mm radius on the end of a 6mm square piece of silver steel I could align the cutter above the stock and mill down but there is a remnant at the front to remove which to date it seems in error I have removed by moving the end mill though the entire 6mm thickness.

Hope all this makes sense, if not a will put up a drawing.

Chris

Hi Guys,

Provided you have a centre cutting supply of end mills is there a rule of thumb as to when you should mill downwards as to sideways. Take for example you want to bore a 1mm radius in mild steel the end mill would likely bend if you used it sideways on. But does this apply to 3mm or 6mm and is there an accuracy implication/

Chris

Posted by SillyOldDuffer on 21/09/2020 16:41:51:

Posted by Chris TickTock on 21/09/2020 14:55:05:

...

Anyway I have attached a photo of my first, second and third attempt. The third when polished up would work, is a fair product but will hopefully get better with a tweek here and there in future.

...

If your No 1 were my first attempt I'd be pleased with it. Although I've picked up several tricks since retiring into Model Engineering, tackling a pinion like that would be a new challenge for me and highly likely to go wrong.

Expectation management is all part of the game. Sooper-dooper equipment and materials with a dash of good advice doesn't guarantee instant success; we have to develop skills. And recognise it takes time and they're unlikely to develop in a straight line. Not uncommon for second attempts to take a step back, and for number 3 or 4 to leapfrog ahead. Or for skills to plateau before improving again.

Main thing is to not be discouraged by poor results: take a break, ponder the problem, and try again.

Dave

Dave,

Wise words 'expectation management', I expected it to be easier than it was. Of course it will become so with practice, providing I learn.

chris

Update after re think

I think it might be beneficial for me to post my thoughts after attempting and succeeding cutting a pinion.

Firstly it is not easy, take your eye off the ball and you will readily cock it up.

Secondly the method I used was given to me by Jerry Kieffer an American horologist and craftsman, some folk despise his machinist stance others like me admire him. Jerry has always been patient and polite and I respect him as I do to all who post with good intent. Having said that Jerry is really patient and kind to give advise but you have to learn to use your machinary well and think for your self at the end of the day.

This was a good example of a relative greenhorn taking on a fairly difficult task. I cocked up many ways until i thought why. The main reason was lack of experience and yes...tiredness.

Thirdly I have looked at alternative ways of making a pinion and in particular Mike Crossfield has been very kind in helping out on this. As far as I can best fathom from looking at Mike's way there are different ways to achieve the same outcome and I cannot see why one is superior to the other. Mikes cutter will possibly reduce vibration so will be something for me to try when I have a few spare hours to compare.

Anyway I have attached a photo of my first, second and third attempt. The third when polished up would work, is a fair product but will hopefully get better with a tweek here and there in future.

Regards to all

Chris

Edited By Chris TickTock on 21/09/2020 14:55:38

Your right John on all counts. Looking at everything it might be the case I heated to orange as opposed to red whilst hardening. What are the effects of over heating by this margin, possibly 100 degrees C above. In future only remedy is reducing light. All these small points add up.

Chris

In order not to attempt walking in to many directions at the same time i am sticking with but paying close attention to detail of the single point cutter.

I am wondering if a M42 end mill will cut a radius on HSS steel on my Sherline mill. HSS steel simplifies things as I believe it has the same hardness as hardened silver steel and gauge plate.

Whilst there seems a consensus of speed between 200 to a max 500 I am yet to understand if too slow a feed rate can cause issues, obviously too fast feed could.

Chris

Very helpful posts thanks to all. I have also been advised that cutting mild steel if poor quality may not be easier than cutting silver steel. The 1/4 square silver steel I have been using is old stock. I am minded to try 1/4 square gauge plate which is obtainable for a cutter. Is there any issue in using gauge plate, I take it it must come machinable but will look into it, otherwise I will get a new source for Silver steel (will check links)?

Having slept on this overnight I had a bad day yesterday, disappointed at the results but now see a few tweeks and fresh thinking I will be there.

Chris