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I need to cut chamfers into x64 pieces of mild steel - any advice?

I need to cut chamfers into x64 pieces of mild steel - any advice?

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John Reese27/09/2021 00:38:06
986 forum posts

John,

I doubt you will find the repeatability you want using an abrasive belt or disc. The V-block and clamp shown in several posts would work extremely well in a vertical milling machine. Just clamp the v-block to the table. If the v-block is long enough you may be able to fit two parts onto it. In that case you would want two clamps, each being over one part. You should substitute a length of silver steel for the drill bit shown. If the job is done on the mill it would be permissible to have clamps protruding above the work.

SillyOldDuffer27/09/2021 10:55:39
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Posted by John Smith 47 on 20/09/2021 16:20:04:
Posted by Rod Renshaw on 20/09/2021 15:22:43:

Usual advice from the makers of diamond "whetstones" and wheels is to use them only for hard materials (carbide or ceramic etc) and not steels which are mostly "soft" in this context, and to use only very light pressure. Diamond is very hard but rather brittle, too much pressure will either fracture the diamonds or tear them from the wheel, and as has been said soft materials will clog the surface.

Rod

My SHARPAL Diamond Whetstone is specifically designed for use with knives which one tends to find are made out of steel.

I can see no mention of "a very light pressure". In fact I have heard people claim that a light pressure is bad for a diamond whetstone and that they prefer to be worked hard.

Water and a nylon scrubbing brush are suggested for removing of any metal particles that get stuck onto the diamond stone.

J

John,

Never draw conclusions from a sample of one! In general Rod's advice is correct. Diamond whetstones are designed for hard materials and clog easily when misused. Mild-steel is very soft compared with the stainless steels used to make knives. There's a high risk of failure.

Once a diamond wheel has been clogged by misuse it may or may not be practical to clean it. It's unpredictable - only trying it will prove whether what's wanted in your workshop will work or not and the smart money is on not!

As to diamonds and pressure, this varies all over the place too. It's because abrasive systems are carefully tuned to work well on specific targets. Sandpaper doesn't work well on hard metal, and Emery Paper doesn't work well on soft wood. Diamond drills are designed to take heavy pressure, most diamond files aren't.

Having the right tool for the job makes light work of most problems. Being pushed to extemporise by shortage of space, money and skill can be an expensive time-waster. It doesn't take many purchases of disappointing kit to add up beyond the cost of paying someone else to do the work, or saving up for an appropriate workshop. Keep a sharp eye on cost versus progress!

I use machines to support experimental work rather than modelling and my projects have a high failure rate. The main cause is me. Be even worse if I didn't have a basic collection of effective tools! I make a fair few simple parts that could be made with a hand-drill, hacksaw, files and a vice, but this is impractical. My milling machine is much faster, more accurate and requires less skill: well worth the investment! You have my sympathy - improvising is really difficult, especially for beginners. If it turns nasty, be ruthless - pay someone with the right equipment to do the work.

Dave

Nicholas Wheeler 127/09/2021 12:57:40
739 forum posts
51 photos

Being ruthless can also mean scrapping existing parts or work because a redesign can make them better/easier/quicker/cheaper. That's one of the reasons why rough and ready prototyping as soon as possible is the modern design approach

Tony Pratt 127/09/2021 13:50:27
1692 forum posts
8 photos

This post has been trundling on for nearly a month, as my kids used to say 'are we there yet'?frown

Tony

Baz27/09/2021 16:04:41
578 forum posts
2 photos

Totally agree with you Tony.

John Reese27/09/2021 17:08:13
986 forum posts

THE END, I hope.

John Smith 4727/09/2021 23:39:37
231 forum posts
11 photos
Posted by John Reese on 27/09/2021 17:08:13:

THE END, I hope.

Wait there appears to be a local culture here that I am unfamiliar with.

Why is 'trundling' so offensive?
I mean why is anyone reading this post if they are bored with it.
Serious question.

Personally, due to the fact that I have a lot of other things going on in my life, my time is only available for this sort of dialog on a very erratic basis.

Maybe I should only private message individuals after X days has passed on whatever thread it is (??)

Regarding the diamond whetstones, to be fair, I have read firm, diametrically opposite opinions. Some people say that they LIKE being worked really hard, and that gentle action bluntens them, other people including Rod (if I understand him correctly) seem to think that one should be gentle with them.

Either way, in my experience even gentle action on a new whetstone can definitely tear away some loose diamonds. You can feel them. And they make a huge mess off the ground surface. And so as soon as you feel them grinding away, it's probably best to clean them off.

But Rod's advice not withstanding, I am perfectly happy with my diamond whetstone, but only for the purpose of putting the finishing touches to the chamfer. Yes mild steel does start to clog it up but if you clean the think with either lapping fluid + a cloth or with water and an nylon brush you can get rid of most of the clogging. This works fine for me, anyway.

Regarding John Reese's advice yes, that makes sense. I have tried using the MF70 and I do get very repeatable results, but the real problem is that it's too slow. So I would need to buy a better (more powerful, slower but higher torque) milling machine than the Proxxon MF70. Possibly a BFW 40/E or its predecessor BFW 36/E (??), although it sounds like the latter can only draw 100watts compared to BFW40/E's 250watts.

Pete.28/09/2021 03:46:24
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638 forum posts
102 photos

Have you tried your current machine with an actual good quality HSS end Mill?

John Smith 4728/09/2021 18:31:55
231 forum posts
11 photos
Posted by Pete. on 28/09/2021 03:46:24:

Have you tried your current machine with an actual good quality HSS end Mill?

That's a good prompt.

I have cut all the parts I need for now, but when I need some more/when I have time I' was planning to have a go with one of these:
"Axminster 4 Fluted Carbide End Mill - 3mm"
https://www.axminstertools.com/axminster-4-fluted-carbide-end-mill-3mm-504861

I wasn't very sure how best to cool/lubricate it.

I tried this waxy stuff "Burr Life, Cut Lube Lubricant"...


... however it's too waxy and more or less just flies straight off!



So next I am planning to use some "Rocol RDT Compound" which was highly recommended by a shop assistant who had firm opinions on the matter:


J

Dave S28/09/2021 18:44:10
223 forum posts
47 photos

Coated carbide on mild steel and a machine that isn’t setup for full flood I would try no coolant at all.

Also go look at MSC direct for *much* better choice and prices.

Dave

John Haine28/09/2021 20:08:14
4170 forum posts
242 photos

Ditto, with a carbide mill on MS tale it slow with no coolant. Arc Eurotrade (advertise on this site) are also a good supplier for cutting tools. That "mitre" cutter you posted looks quite unsuitable, either buy a mitre cutting mill bit or mount the work at 45* (in vee block) and use an ordinary end mill. You can also mitre with the side of an ordinary countersink, the multi-tooth variety, again take it slow.

John Reese28/09/2021 20:18:08
986 forum posts

A proper countersink works quite nicely for milling chamfers as John Haine suggested. Using one allows the work to stand vertical in the vise.

JasonB28/09/2021 20:19:16
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Remember John can only hold upto 3mm shank dia in his Proxxon which will limit the choice of cutters

JohnF28/09/2021 20:21:06
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1099 forum posts
183 photos

A bit late to the party and have not read all the posts but here are a few photo's of a jig I made many years ago to manufacture small dovetail pieces with a 60* angle but you could make one to do 45* in a similar form, I just mounted it in the lathe and took a facing cut, there is a sample I cut tonight to show the result -- I did not have a mill at the time i made this but if I was doing what your early photos show I would make a jig to hold several pieces and in a vice on the mill and use a standard endmill. John

6d8a142b-2796-4e9d-ad9a-009f78efb0fc.jpeg

a5e0ebf6-dcb3-4dd0-95cf-d3599bb77326.jpeg

3540a29c-07f1-42b0-9fae-b01a15bc9888.jpeg

462c5727-30a2-4874-ad82-c36516f197c8.jpeg

John Smith 4729/09/2021 11:49:09
231 forum posts
11 photos
Posted by John Haine on 28/09/2021 20:08:14:

Ditto, with a carbide mill on MS tale it slow with no coolant. Arc Eurotrade (advertise on this site) are also a good supplier for cutting tools. That "mitre" cutter you posted looks quite unsuitable, either buy a mitre cutting mill bit or mount the work at 45* (in vee block) and use an ordinary end mill. You can also mitre with the side of an ordinary countersink, the multi-tooth variety, again take it slow.


1. Out of interest, is there an actual advantage of not using coolant. Or are you saying it is just not necessary?

2. Just to get clear, do we agree that Axminster is incorrect when they say that "coolant is essential"
https://www.axminstertools.com/axminster-4-fluted-carbide-end-mill-3mm-504861

3. In this context, if no coolant, is there also no need for a lubricant too?

4. Thanks for the tips re Arc Eurotrade & MSC direct. Both websites are quite flawed (painfully slow to load, poor quality photos, search field loses your search keywords) but a wider range and prices look good.

Yes, Axminster are painfully expensive and do have a smaller selection of products on offer, but they tend to give more information about their products. If their information is incorrect, then that is a big problem for them.


5.
> That "mitre" cutter you posted looks quite unsuitable

John Haine - Are you saying that there is something wrong with THIS tool that I have been using?


"Busch Burr Stone Setting 8.0mm"
Made from HSS
https://www.cooksongold.com/Jewellery-Tools/Busch-Burr-413-Stone-Setting-8.0mm-prcode-941-043

If so, can you suggest a specific better quality tool?

Yes, currently I can only go up to 3.2mm diam shaft which is the largest collet that came with the MF70.

JasonB29/09/2021 12:10:06
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I would not go with what Axminster say, unless you have flood coolant you are more likely to damage the carbide cutter by applying small amounts of lubricant and in small amounts no liquid will really do much cooling. So run carbide dry.

If you are finding MSC and ARC slow to load then I would think that is a problem your end maybe with a slow connection or machine as they are both fine for me and have far more (correct) info about their cutters than what Axi have on theirs

If you use the side of a cutter then you don't need a chamfer tool, just hold it like you have been doing in the vee block and use the edge of a straight sides tool such as the 3mm dia one here which has a 3mm shank

John Smith 4729/09/2021 15:53:42
231 forum posts
11 photos

JasonB:

1. That's interesting to learn that lubricant in small amounts can damage carbide cutters. I think that I read somewhere that lubricants can stop the heat from getting away fast enough...

2. Wrong, although they both seem much faster now, both MSC (www.mscdirect.co.uk) and ARC (www.arceurotrade.co.uk) were 100% definitely running slow. In particular their search results were both taking 20 to 30 seconds to load, whereas my own internet connection was running at full speed (60Mbps) and every other site I visited immediately before and afterwards were loading more or less instantly.

3. Yes my plan was to use this end mill:
"Axminster 4 Fluted Carbide End Mill - 3mm"
(www.axminstertools.com/axminster-4-fluted-carbide-end-mill-3mm-504861)
...which the manufacturers call "both solid carbide AND coated" and that the thickness of the coating is "between 4 to 6 microns". Do you think it will suffice?

Reading up on your suggested "ARC Premium TiAlN Coated Carbide End Mills" with its Micro-Grain Carbide, the TiAIN (titanium aluminium nitride) coating does sound impressive. It sounds like it can cope with high temperatures well. At just £11.74 it's pretty low cost. I might just buy one right now. I would be buying the 3mm version.

Questions:
- It only has 3 flutes. Do you think that will suffice for side milling?
- What speed should I run my Proxxon MF70 at? Choice: 5K to 20K RPM
- If I used it to slice up 1mm thick mild steel sheet, realistically how long would you expect it to last in terms of distance of cut (e.g. cm)?

Edited By John Smith 47 on 29/09/2021 15:55:01

Dave S29/09/2021 15:59:18
223 forum posts
47 photos

“Coolant” with carbide is mostly to flush the chips away.
The need to cool the tool, especially with the limited power of your Proxxon is minimal.

Intermittent coolant on carbide tends to thermally shock the tool, and is more likely to lead to poor tool life.
Carbide coatings have been developed to increase tool life without coolant.

I mostly use coolant when I want to be able to measure a part soon after cutting - it helps to keep the part at near to ambient temp - so my measurements are more likely to be accurate…

I would trust MSC and Ketan for info more that Axminister.

Dave

John Haine29/09/2021 16:14:08
4170 forum posts
242 photos
Posted by John Smith 47 on 29/09/2021 15:53:42:

JasonB:

1. That's interesting to learn that lubricant in small amounts can damage carbide cutters. I think that I read somewhere that lubricants can stop the heat from getting away fast enough...

2. Wrong, although they both seem much faster now, both MSC (www.mscdirect.co.uk) and ARC (www.arceurotrade.co.uk) were 100% definitely running slow. In particular their search results were both taking 20 to 30 seconds to load, whereas my own internet connection was running at full speed (60Mbps) and every other site I visited immediately before and afterwards were loading more or less instantly.

3. Yes my plan was to use this end mill:
"Axminster 4 Fluted Carbide End Mill - 3mm"
(www.axminstertools.com/axminster-4-fluted-carbide-end-mill-3mm-504861)
...which the manufacturers call "both solid carbide AND coated" and that the thickness of the coating is "between 4 to 6 microns". Do you think it will suffice?

Reading up on your suggested "ARC Premium TiAlN Coated Carbide End Mills" with its Micro-Grain Carbide, the TiAIN (titanium aluminium nitride) coating does sound impressive. It sounds like it can cope with high temperatures well. At just £11.74 it's pretty low cost. I might just buy one right now. I would be buying the 3mm version.

Questions:
- It only has 3 flutes. Do you think that will suffice for side milling?
- What speed should I run my Proxxon MF70 at? Choice: 5K to 20K RPM
- If I used it to slice up 1mm thick mild steel sheet, realistically how long would you expect it to last in terms of distance of cut (e.g. cm)?

Edited By John Smith 47 on 29/09/2021 15:55:01

3 flutes fine.

See **LINK** for a feeds & speeds calculator. It recommends ~10000 for a 1/8 cutter in mild steel.

I wouldn't use an end mill for that - better to buy steel strip and hack short lengths off it, use the mill to square and chamfer them.

Coolant is to cool the cutter, not lubricate it, you don't want it to slide by definition. Small amounts of oil just make a mess, stick the chips to the cutter, and don't help to keep it cool.

Andrew Johnston29/09/2021 16:44:20
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6264 forum posts
677 photos

To answer some of the OP's questions:

Yes, there can be significant disadvantages to using coolant. Some coatings, such as TiAlN, need to run hot (many hundreds of degrees) to work properly. Commercially it's a pain to have coolant being thrown around, and it decreases the value of the swarf.

Axminster is incorrect to say coolant is essential. All my manual vertical milling is done dry. I use flood coolant on the CNC mill, mainly to wash away swarf. Flood coolant is often used on the horizontal mill, as I mostly use HSS cutters and take heavy cuts (5hp motor).

There's no such thing as "solid carbide". Carbide tooling consists of tungsten carbide particles in a matrix of, usually, cobalt.

The Arc premium cutters are very good, but they're a waste of money on small mills as there's isn't enough motor power to make best use of them.

The finish when side milling is dependent upon chip load, not on the number of flutes. The profile on these parts was machined with a 2-flute ballnose cutter and a 3-flute square endmill:

spectacle1.jpg

I'd run a 3mm cutter in steel at 7500rpm for profiling and 6000rpm for slotting.

Soluble oils (water/oil) mix are primarily for cooling with some lubrication. Neat cutting oils are primarily for lubrication under high cutting pressures with little cooling. That's why neat cutting oils are often seen on gear cutting machines.

Andrew

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