Milling Metals With a Router

[RWoody]

For example, using an M8 bolt gives you 1mm per revolution (on a standard-pitch metric thread), or M10 does 1.5mm. I used my T11's through-table height adjuster to do this (M10 pitch).

Being pedantic here, M8 has a pitch of 1.25mm. M6 has a pitch of 1mm :wink:

Also being pedantic, Common M8 pitches are 1.25mm or 1.5mm (fine or course)

Gerry

Interesting :? I can't see, without a diagram or physical representation, how an M8 can have two different pitches. My understanding, which now falls into question , was that M8, for example, was a specific diameter AND pitch. I haven't work with metal for a good many years, so maybe I'm missing something fundamental here. Apologies if something is very obvious, which I'm overlooking. Anyway, I CAN see two different pitches on the same diameter bolt; it's just that I can't for what I thought was a 'fixed' or 'standard' size M8.

Thanks for this information.

 

[RWoody]

do you know of any metalworkers in your area? (Probably not else you would already have tried them) Perhaps a look on a metalwork forum might bring up a new acquaintance? Doing the bulk of the work on a milling machine and finishing off by hand filing sounds the best and safest way to me.

Woody, what's quoted in the post above, there's got to be a small workshop near by.

I've seen many an accident with milling machines never mind a router.. :shock: ..vibration is your worst enemy.

SS.

Sure, ss03947, this is why I've come to this forum, as sometimes danger is closer than one thinks Thanks for the warning anyway.

 

[RWoody]

just buy a milling machine, simples.

That's all well and good, but the point of this whole exercise is not to buy yet another machine! If I can use or adapt my existing machinery, then so much the better, not to mention extra cost - especially as I'm unlikely to need to mill again like this. If I do, and it's ongoing for any reason, then of course I'd consider another machine, when space and funds permit.

 

[Gerry]

Interesting :? I can't see, without a diagram or physical representation, how an M8 can have two different pitches. My understanding, which now falls into question , was that M8, for example, was a specific diameter AND pitch. I haven't work with metal for a good many years, so maybe I'm missing something fundamental here. Apologies if something is very obvious, which I'm overlooking. Anyway, I CAN see two different pitches on the same diameter bolt; it's just that I can't for what I thought was a 'fixed' or 'standard' size M8.

Thanks for this information.

There are a variety of pitch/Diameter combinations in Metric screw threads. It's part of my job to measure and calibrate screw plug gauges to BS3643-2-2007

http://en.wikipedia.org/wiki/ISO_metric_screw_thread

Gerry

 

[Eric The Viking]

I was originally referring to the common sizes (and forgetting which was which!).

It's easy to find out what you have, with bolt and a decent ruler: count eleven ridges along the bolt, and measure the distance. Do twenty if it's a small bolt!

Most of the commonly available stuff is metric 'coarse' pitch. As Gerry says, there's usually a fine pitch defined, too, especially for the larger sizes. They're rarely seen in DIY/construction, but I've come across them in the motor industry, for example the M10* bolts securing seatbelt webbing straps in our old Passat were fine pitch. The reasons are obvious - extra strength and less likelihood of unwinding by itself.

Similarly, there are uncommon metric bolt sizes. For example M7 is defined but hardly ever used in everyday applications, and I was amazed to find it was used for the battery clamp bolt on daughter's Rover 200. I now own three M7 bolts (always have spares!), which weren't cheap and had to be sought out locally, but I replaced the fitting with M8 (which everyone else uses) at the first opportunity.

People used to grumble about the range of non-metric threads, but they all had a purpose. Some were easily done up/undone (Whit.), some had strength (BA, UNC, UNF) - you could use the right thread for the task. In a metric world one size fits all, unless you're in manufacturing.

E.

*might have been M12 - it was a long time ago. I still have the bolts somewhere...

 

[RWoody]

Interesting :? I can't see, without a diagram or physical representation, how an M8 can have two different pitches. My understanding, which now falls into question , was that M8, for example, was a specific diameter AND pitch. I haven't work with metal for a good many years, so maybe I'm missing something fundamental here. Apologies if something is very obvious, which I'm overlooking. Anyway, I CAN see two different pitches on the same diameter bolt; it's just that I can't for what I thought was a 'fixed' or 'standard' size M8.

Thanks for this information.

There are a variety of pitch/Diameter combinations in Metric screw threads. It's part of my job to measure and calibrate screw plug gauges to BS3643-2-2007

http://en.wikipedia.org/wiki/ISO_metric_screw_thread

Gerry

Yes I can see it's pretty technical/complicated, though I understand what's being said, just - having just read the wikipedia definition. Thanks.

I think I was struggling to get my head around the height vs pitch ratio; in as much as for the same ratio, if the depth of thread was the same for one 8mm bolt compared to another, then of course the pitch would then have to be the same. I'm not sure I'm explaining that very well, but I hope you get the gist.

Anyway, all interesting to me, as is anything technical really. Thanks for your input.

 

[RWoody]

I was originally referring to the common sizes (and forgetting which was which!).

It's easy to find out what you have, with bolt and a decent ruler: count eleven ridges along the bolt, and measure the distance. Do twenty if it's a small bolt!

Most of the commonly available stuff is metric 'coarse' pitch. As Gerry says, there's usually a fine pitch defined, too, especially for the larger sizes. They're rarely seen in DIY/construction, but I've come across them in the motor industry, for example the M10* bolts securing seatbelt webbing straps in our old Passat were fine pitch. The reasons are obvious - extra strength and less likelihood of unwinding by itself.

Similarly, there are uncommon metric bolt sizes. For example M7 is defined but hardly ever used in everyday applications, and I was amazed to find it was used for the battery clamp bolt on daughter's Rover 200. I now own three M7 bolts (always have spares!), which weren't cheap and had to be sought out locally, but I replaced the fitting with M8 (which everyone else uses) at the first opportunity.

People used to grumble about the range of non-metric threads, but they all had a purpose. Some were easily done up/undone (Whit.), some had strength (BA, UNC, UNF) - you could use the right thread for the task. In a metric world one size fits all, unless you're in manufacturing.

E.

*might have been M12 - it was a long time ago. I still have the bolts somewhere...

Yes, Eric, I can see why specialists would prefer non-standard bolts for specific applications, as they're simply more suited to the job; and as you say, fine pitches indeed do have less tendency to work loose, for bolts used in situations where vibration is present. The shallower (meaning 'steeper' in this case) angle of the thread to the shank, has less tendency to slip, and hence work loose. One can also tighten to a greater compression force, for the same leverage (Nm poundage); though also making it easier to strip the threads, especially as the threads themselves would be thinner, so have less material within them. Interesting.

Thanks to you too.

 

[seaco]

I have used a straight and round over router cutters 1/2" to cut aluminium it cut really well I was surprised how easy it was, I was making a jig for my router out of 8mm thick ally and needed to make a recess in the middle for the router base so I just plunge cut it about 1mm at a time then I used the round over around the outside to make it look more professional...

 

[RWoody]

Thanks for your message, Lee. I can see that in your situation you'd have been less limited, by virtue of the fact that as you point out, you milled with a plunge action. Vibration and lateral cutting issues wouldn't have therefore have caused much difficulty. The potential problem I had, was one of long, lateral cuts, where the router, or workpiece, would me moving across the face of the cutters.

I've decided what I'm going to do (having been busy on another job for a customer) and that is to 'file' the piece of brass I have which is so very near to fitting already, as suggested on this forum.

The other, much smaller, guide rail I shall purchase something made of a plastic-like substance. I have to look into this, and choose something easier to work with that also gives good longevity, so not prone to wear too quickly.

Then I shall purchase an Incra mitre gauge, and fit rivet-like pegs to the rail, which will slot into both the brass rail and the 'plastic' one. Having the 'pins' set/fixed immovably in the mitre gauge means that the gauge itself will remain in tact and square, as the wear will take place on the parts I've had to make up; so when things work loose eventually, I can replace the home-made parts without affecting the mitre gauge. Doing it this way would be preferable to having the holes drilled into the mitre gauge, and the pegs in the replacement parts, as when things work loose, it'd be the holes in the Incra mitre gauge itself. I really don't want to have to make, adjust or otherwise play around with that if I can avoid it. I'm not sure I've explained this very well; but I hope you understand what I'm getting at?

A big thank-you to everyone who has contributed. This is now hopefully solved. If it works really well, then I might photograph what I've done, if anyone would be interested to see? However, it it's only mediocre, then I won't feel like broadcasting it around as much.

All the best.

Ian

 

[seaco]

Glad your sorting it out pics are always welcome...