Regrinding Milling cutters – worth it or not?

[Rob WalkerParticipant @robwalker86754]

[Rob WalkerParticipant @robwalker86754]

HI,

Just acquired a new (to me) mill that I am restoring. It came with a bucket load of old cutters, collets etc.

With a wire bush the cutters came up ok and i was hoping for advice on if/where they can be re-ground and if its worth it?

Mostly looking at horizontal cutters and twin flutes etc with a diameter over 1"

R

[old martParticipant @oldmart]

The larger HSS endmills cost quite a lot new, and if you can find a firm which can regrind them for you, then go ahead. There is a firm that I know of, Horley Tools from near Gatwick airport which are recommended. For hobby use, the exact size will not be important and telling the cutter grinder should result in a slightly reduced cost.

 By the way, welcome to the forum.

Edited By old mart on 26/06/2023 20:06:38

[Rob WalkerParticipant @robwalker86754]

Posted by old mart on 26/06/2023 20:05:45:

The larger HSS endmills cost quite a lot new, and if you can find a firm which can regrind them for you, then go ahead. There is a firm that I know of, Horley Tools from near Gatwick airport which are recommended. For hobby use, the exact size will not be important and telling the cutter grinder should result in a slightly reduced cost.

By the way, welcome to the forum.

Edited By old mart on 26/06/2023 20:06:38

Many thanks, and thanks 👍

[Trevor Drabble 1Participant @trevordrabble1]

Would also recommend Abbco in Nottingham , who were originally sited next to the old Myford factory. They are on 0115 9290700. No connection with company .

[HuubParticipant @huub]

Grinding the tip of an end mill is not that difficult. Put the end mill in a hex collet, set the mill on a 3° angle and grind the flutes with a (dremel) diamond disk (0.1 $ on ebay). They will be as new.
If you grind them often (like me), they won't be usable to plunge a hole but that is a minor.

Once a year, I grind my end mills, drills, slitting saws, roughing end mills on the CNC (mini) lathe with a Dremel in the tool post.
You have to cover all other machines with blankets and still have to clean the ways from all machines to get that HSS dust away. So after grinding, all my machines get their annual maintenance.

I only grind HSS tools (HSS M2). I don't grind tools that contain cobalt because cobalt dust is toxic.

[Clive Brown 1Participant @clivebrown1]

Whether it's worth it depends on what you want to machine. It's true that new, large cutters are pricey but regrinding old cutters, especially as a number of different "one-offs" will still be a significant cost. Big end mills aren't hugely useful for the normal run of model engineering, hoirzontal cutters even less so. Could be different of course if you're into big stuff.

[Rob WalkerParticipant @robwalker86754]

Many thanks for the pointers and contacts to all that have helped.

I'm pretty happy grinding drills and smaller end mills are a similar philosophy with a bit more setup. The ones I really want done professionally are some more complicated ones, a 3"x4" slab cutter (spiral fluted edge) and a few end mills with round noses 1”+ diameter etc

Machine capable of big stuff and just wanted to have the few larger cutters up to grade for Justin (case)👍

Thanks for the leads, will phone around 👍

[Anonymous]

Out of curiosity what is your mill? You need a good few horsepower to get the best from a slab mill:

Andrew

[Brian Baker 2Participant @brianbaker2]

Greetings, having now, finally, after years in the hobby, got into regrinding cutters, I can tell you that reground, sharp cutters make a noticeable difference in my work produced. Cuts are easier, and leave a better finish than using a cutter from the "cutter box".

I built a Stent, which worked well, but now have a Quorn, built by a deceased friend, which I prefer. Using a diamond wheel they could not be sharper.

Regards

Brian B

[Rob WalkerParticipant @robwalker86754]

Mill is a Victoria/Elliott U2 – 4HP.

A recent acquisition, a tool/project combo. She has been sat a while and needs a good overhaul to recommission to a fully serviceable condition. She runs nice and quietly in all gears and 2 out of 3 power feeds are functioning as they should. When I tested her at the sellers property it took a bit of tinkering to free off some of the feed controls and I'm hoping that once the feed control gearbox comes apart, the issue will be rectifiable.

Initial cleanup underway to see whats under the grime, initial inspections are encouraging.

[Nigel McBurney 1Participant @nigelmcburney1]

I use a well equipped Clarkson cutter grinder,I bought it at a sale as I had used one at my first job,so I was familiar with the machine,works practice there was to only grind the the face of small end mills/slot drills,the helical side teeth were rarely ground ,the majority of work was very light shallow cuts in brass castings. helical cutters for the horizontal mill were ground on te helix ,dedlock cutters used on cast iron were ground all over. If small end mills are used at the correct speeds and feeds they will last a long time, nowadays I think too many home enthusiasts are too keen ,perhaps impatient and run their cutters too fast and cause premature wear. Andrews got it right with his A&S mill ,big cutters and decent vice with arbour support really close to the cutter to give maximum support to the arbour,If large batches were being machined with maximum cut then very often a second arbour support would be employed on the other side of the cutter,particularly when the cutter set up was a pair of large side and face cutters with a roller/slab mill in between.

[Anonymous]

Posted by Rob Walker on 27/06/2023 09:09:17:

Mill is a Victoria/Elliott U2 – 4HP

That's a good solid mill, will have no problem driving slab mills. Universal as well, which is a nice feature to have, especially if you want to make helical gears.

Like Nigel I have a Clarkson T&C grinder with the accessories to sharpen slab mills and S&F cutters. Thus far I've never needed to use it, but the facility is there when I do.

With a horizantal mill you really need to understand the cutting forces and clamp the work accordingly. Slab mills and S&F cutters want to lift the work, especially with deeper cuts. I learnt the hard way that the laissez aller clamping methods I could get away with on the Bridgeport are nowhere near adequate for the horizontal mill.

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Posted by Rob Walker on 26/06/2023 22:26:29:

…

Machine capable of big stuff and just wanted to have the few larger cutters up to grade for Justin (case)👍

Thanks for the leads, will phone around 👍

Can you let us know quotes?

It's cost versus value question, where the answer depends on circumstances.

My workshop has a basic vertical hobby mill. It's mostly used for light detail work, not hogging metal. Not having a horizontal mill means paying to sharpen horizontal cutters has no value to me. Might be worth having a big helical cutter sharpened for a special job, but I rarely use them. Those I bought with the mill 'justin case', are still sharp, and a few have never been used. This is why experienced machinists don't recommend buying sets – there's a risk of wasting money on tools that never get used.

Same problem with buying second-hand and finding it comes with a box full of random cutters, many blunt. Financially, there is no point in having them sharpened unless they're going to be used.

There's an argument in favour of owning tools 'just in case'. It's time saved when a new job suddenly requires a particular tool and there's a painful delay whilst one is ordered and delivered. Sod's Law guarantees that urgently needed tools are always out-of-stock.

Trouble with buying 'just in case' is it costs a fortune, takes up space, unusual tools are hard to find in deep storage 10 years later, and grieving relatives will probably dump the whole lot into a skip when the time comes.

I guess most Model Engineer's target our tool-spending on things that are definitely needed rather than stocking up on the off chance. Bargains are always welcome, but some thought goes into 'is this worth it?'

The value of sharpening cutters is strongly influenced by what I do with them – light detail work at gentlemanly hobby rates! Cutters last a long time in my workshop because I don't cut a lot of metal quickly. Others work their machines much harder, and value of sharpening becomes more evident. Professional workshops have to work quickly and efficiently, time is money. Amateurs are between two extremes. Some collect tools and never use them! Others are as busy as a busy commercial operation. Most are in the middle, and I suspect tool sharpening is a low priority.

Not resharpening is something of an industry trend. In the good old days most machine shops resharpened in-house. These days that's unlikely because third-party specialists do the same job cheaper and better. In the smaller sizes CNC cutters are often single-use, replaced when worn. They're recycled rather than resharpened. I think this is partly economics and partly because resharpening alters cutter size, bad news when a machine auto-changer expects cutters to be standard sizes.

I'm not sure resharpening is high value to most Model Engineers. I've been a cynic since reading the accusation in an old ME magazine that almost every workshop in the land had an unfinished Stent and Quorn under the bench! In my case, most of the time, it's easier to buy new. I'd think differently if my workshop took a week to blunt a big cutter costing £100 plus that could be resharpened in a week for £20. Then I buy 4 of them, so one was always cutting, with one out being resharpened, and two in reserve. In this scenario the initial investment is £400, plus £1040 per year on sharpening. Assuming each cutter can be sharpened 5 times, I also buy one new cutter per month (£1200). But I'm not in that game – my needs are met by occasional orders for a few new cutters.

Dave

[Rob WalkerParticipant @robwalker86754]

Posted by Andrew Johnston on 27/06/2023 11:00:03:

Posted by Rob Walker on 27/06/2023 09:09:17:

Mill is a Victoria/Elliott U2 – 4HP

That's a good solid mill, will have no problem driving slab mills. Universal as well, which is a nice feature to have, especially if you want to make helical gears.

Like Nigel I have a Clarkson T&C grinder with the accessories to sharpen slab mills and S&F cutters. Thus far I've never needed to use it, but the facility is there when I do.

With a horizantal mill you really need to understand the cutting forces and clamp the work accordingly. Slab mills and S&F cutters want to lift the work, especially with deeper cuts. I learnt the hard way that the laissez aller clamping methods I could get away with on the Bridgeport are nowhere near adequate for the horizontal mill.

Andrew

Work holding is also on the 'to do' list, my whole philosophy with the milling set up is 'big and heavy all-round', future proofing for anything that i might wan to do later down the road.

Fortunately I have 2 vertical heads for it, the standard single swivel and the 'true' universal with the MT3 taper. The MT3 will likely get the most use as my Lathe has this taper and therefore I can use some of the tooling interchangeably. Just need to make a new retained drawbar as I thing the original is 3/8 or something similar, need a metric one for my tooling

[old martParticipant @oldmart]

You will probably get the most use out of an er32 to MT3 collet holder. The only drawback will be the limited maximum rpm. If the horizontal spindle size is ISO or BT40, er 32 tooling is also readily available, so you have capacity for up to 20mm cutters. Any bigger and shell mills are the easy option. Full horizontal cutting of slab materials will be used rarely by hobbyists, but having a few sharp cutters just in case will be useful from time to time.

[Anonymous]

Posted by Rob Walker on 27/06/2023 11:35:21:

..'big and heavy all-round'…

To an extent, but not always needed. In the picture in my last post the slab mill is cutting two steel blocks, total width of cut is 1.5". The depth of cut was 2.5mm. I tried a DOC of 5mm, but on the initial cut the work was lifted from the vice as there was significantly more upwards force than with a 2.5mm DOC. On the other hand in this picture there is nothing clamping the steel block down to the table:

There is a steel block clamped to the table out of sight on the left to react the horizontal cutting forces. The workpiece is held in place with the three eccentric hexagon clamps on the right. The DOC is shallow, just enough to remove the hot rolled scale. It's all about understanding the magnitude and direction of the cutting forces.

I am envious that you have the universal vertical head. The original thread for the MT3 drawbar will most likely be 3/8" BSW.

On my mill the arbors, and older accessories, are 5/8" BSW whereas for the newer facemills I have needed to make drawbars with M16 threads.

Andrew

[Rob WalkerParticipant @robwalker86754]

Posted by SillyOldDuffer on 27/06/2023 11:31:32:

Can you let us know quotes?

It's cost versus value question, where the answer depends on circumstances.

Same problem with buying second-hand and finding it comes with a box full of random cutters, many blunt. Financially, there is no point in having them sharpened unless they're going to be used.

There's an argument in favour of owning tools 'just in case'. It's time saved when a new job suddenly requires a particular tool and there's a painful delay whilst one is ordered and delivered. Sod's Law guarantees that urgently needed tools are always out-of-stock.

Trouble with buying 'just in case' is it costs a fortune, takes up space, unusual tools are hard to find in deep storage 10 years later, and grieving relatives will probably dump the whole lot into a skip when the time comes.

I guess most Model Engineer's target our tool-spending on things that are definitely needed rather than stocking up on the off chance. Bargains are always welcome, but some thought goes into 'is this worth it?'

The value of sharpening cutters is strongly influenced by what I do with them – light detail work at gentlemanly hobby rates! Cutters last a long time in my workshop because I don't cut a lot of metal quickly. Others work their machines much harder, and value of sharpening becomes more evident. Professional workshops have to work quickly and efficiently, time is money. Amateurs are between two extremes. Some collect tools and never use them! Others are as busy as a busy commercial operation. Most are in the middle, and I suspect tool sharpening is a low priority.

Not resharpening is something of an industry trend. In the good old days most machine shops resharpened in-house. These days that's unlikely because third-party specialists do the same job cheaper and better. In the smaller sizes CNC cutters are often single-use, replaced when worn. They're recycled rather than resharpened. I think this is partly economics and partly because resharpening alters cutter size, bad news when a machine auto-changer expects cutters to be standard sizes.

I'm not sure resharpening is high value to most Model Engineers. I've been a cynic since reading the accusation in an old ME magazine that almost every workshop in the land had an unfinished Stent and Quorn under the bench! In my case, most of the time, it's easier to buy new. I'd think differently if my workshop took a week to blunt a big cutter costing £100 plus that could be resharpened in a week for £20. Then I buy 4 of them, so one was always cutting, with one out being resharpened, and two in reserve. In this scenario the initial investment is £400, plus £1040 per year on sharpening. Assuming each cutter can be sharpened 5 times, I also buy one new cutter per month (£1200). But I'm not in that game – my needs are met by occasional orders for a few new cutters.

Dave

Thanks Dave,

For me the machine was the purchase, along with the major accessories (horizontal setup, 2 original vertical heads and the slotting attachment). The purchase is a project in its own right so I expect there to be a few expenses that, on the face of it are not worth it, but thats restoration!

Looking through the 'boxes of cutters' some are clearly wrecked There are a few however, that are both clean enough to be reground and would serve a purpose when sharp. I'm looking to sharpen a large slab cutter (4" x 3&quot and a couple of larger slot cutters for the horizontal setup only, the smaller cutters if needed are cheap enough. there are a few larger 2/3/4 flute end mill cutters in sizes that are so expensive I would never really buy them new unless there was a very specific (and financially viable) reason! some are easily £100+ each.

I did contact one of the options above and received some quotes. the guy seemed very reasonable and outlined he can regrind anything within reason but doesn't bother with stuff under 1" as its not worth it. General prices as a guide:

20-30mm HSS = £11 ea

30-40mm HSS = £18 ea

40-50mm HSS = £23 ea

3” Slab mill = £30ea

Radii (additional charge)

0-3mm = £10

3-6mm = £15

Corner Rounding

0-3mm = £15

3-6mm = £25

From my perspective, spending £100 on getting a few of the most versatile cutters reground will be beneficial for those bigger jobs rather than buying new. Small stuff, there are plenty of cheaper options for new cutters and I can use ones I have being using horizontally on the lathe.

Thinking of starting a thread on the machine restoration… not sure if there is an appetite for it or not but in my search for information on this particular model its proving to be limited.

And if anyone can help identify these inserts and where I might get some more I would be grateful!…

[StueeeeParticipant @stueeee]

They look very similar to the inserts I use in a facemill here.

The same SNUN 1905xx inserts should fit -the 'ordinary' ones have a similar corner radius to yours. These, not so much…

**LINK**

The last time I looked, Jurassic tools had some SNUN 1905xx inserts for sale on their website (usual disclaimer, just a customer etc.)

[Rob WalkerParticipant @robwalker86754]

Posted by Stueeee on 05/07/2023 16:42:20:

They look very similar to the inserts I use in a facemill here.

The same SNUN 1905xx inserts should fit -the 'ordinary' ones have a similar corner radius to yours. These, not so much…

**LINK**

The last time I looked, Jurassic tools had some SNUN 1905xx inserts for sale on their website (usual disclaimer, just a customer etc.)

Many thanks Stueeee, that's really helpful. Jurassic tools don't have any listed currently but their site is a new one to me and looks like a good place to keep an eye on. The Ebay ones will work for me, the radius is not important as the inserts are canted over in my holder and with luck I can get 4 edges from those, if I don't drive them too deep on each pass!

[Author]

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