Member postings for pgk pgk

Thanks for the vid. I just did exactly the same thing with a new 4-flute and got the same chips.. and lots of cutting oil smoke and a very hot tool. How long would it last like that? But just like a parting tool..less vibes when its working hard.

From another newbie.

Sadly you will have to grind the tool. If you look at 'toms techniques' website where he is squaring the stock on his latest project he does go through the grinding of such tools.

Essentially it's the same grind as a lathe cutting tool.. just because it's presented to the work upside down and it's the tool that's spinning just makes it a bit weird to get your head around (I had to draw myself a few doodles to get it straight) The important aspect I find is gettign the end radius right. For ally it's about 1/16th of an inch typically and you really do have to stone it smooth to get a good finish. It's also better (for me anyway) to use a smaller flycutter when practicable so any slight tramming errors on the mill show up less.. to the point that I re-tram if I put the vice on compared to the mill bed itself. And thats a pain on my mill..one of those where as you tighten the head bolts it just moves a touch and can be a boring fiddle to get right.

Justlike a lathe tool you need clearance below the cutting edge (below on a lathe tool, above on a fly cutter), clearance behnd the cutting edge on a lathe tool is below the edge on the flycutter and end clearnace on a lathe tool is below the free end but behind on the flycutter free edge. Yeah, confusing...

I just had a quick go at chain drilling a small length of 45mm thick cold rolled using a 6mm split point cobalt jobber drill in an er32 collet.. so I could get right to the screw threads holding it and just have about 50+ mm out. Three holes exactly 6mm apart on the DRO with plenty cutting oil.. First hole dead straight, second wandered away from the line by 1mm or so over it's depth and third hole broke into the second about halfway.

I want to get on with the project in hand but I'll try this again sometime with a little more spacing between holes (say 0.1-0.2mm) and/or drilling from both sides to reduce wander amount.

I certainy concede thata better quality endmill would give less vibe issue. It was a decent one that iburnt up.. mostly because it was cuttign so much better and I overdid it.. got mesemerised plunge cutting with it until i realised quite how hot my part had become at those speeds of cut with hand sprayed coolant. Next better endmill will get more respect.

Cheapo chinese cutters from one of those box sets. The problem is vibration I haven't attended to (yet) from the mill stand cabinet. It's not that the mill can't physically do it... sort of harmonic build-up?

I've only tried chain drilling once and obviously didn't get the spacing right.. drill kept deflecting into adjacent hole or leaving too much material between holes. How much allowance do you make for drill wander/depth of chain drilling? (as in how far from the finished edge do you drill)

Jason's drawing is correct.

Using mild steel cutting speed 100sfpm for a 12mm endmill would be 800 rpm .. nearest speed bands were either 560 or 980.. so 560rpm selected. I found that more than 0.25mm cutting depth even on a new 12mm cutter (ither 2 or 4 flute) gave rumbles and judder i didn't like although, yes, if I had to i can force it at anything to full depth. Plunge milling to 1mm short of full depth with 1mm increments to 0.2mm of the edges and then milling to final size in small increments gave me a good finish but the last cut each row again I get a lot of bounce/chatter between the stock remnants and have to peck them away. That put me off the idea of using ordinary drills to remove the majority because the remnants are going to cause lots of chatter cleaning up.

To spare edmills I;ve been squaring up this sort of stock with a flycutter and taught myself to grind them so the finish is as good as an endmill - and cheap. But again more than about 0.25mm depth of cut on a 30mm approx sweep flycutter and the chips start coming off blue and quickly leads to a regrind.

I did think about using my bandsaw but at 50mm thickness and the need to cut again to get the angle for the 'turn' at the bottom was going to be a really slow process for me.

Cross drilling the width I did think about but didn't try.

How about hogging out with an angle grinder or would that cause heat distortion?

fair enough.. it makes sense to me.. but then i know what i mean

Have my subsequent posts made it clearer?

Jason,

It is a theoretical question.. just a slot fully across a piece of mild steel bar stock, say 30 to40 mm thick, then 50mm wide and obviously longer than the 30mm slot width.

I happen to have a chester lux mill.. no power feed. From my own experience I know that tryign to mill such a slot with anything much wider than a 12-14mm endmill makes my machine shake. Equally a slow enough lateral feed full depth with a cheapo endmill generates more friction heat and is slower than plung cutting nibbles away. I have no experience of say a roughing end mill compared to a cheap chinese HSS one.

The whole thing about a hobby is that generally we have time to play as opposed to production speed and wages. So if there is an economic way of going about such slots.. that my question.

I did notice in one of your other threads you used a wide indexed endmill.. can you feed and surface away the depth quicker with something like that for instance?

pgk

I don't have flood coolant on it at the moment (a chester cockup on parts) so taking my time, brushing swarf away and spraying coolant and plung cutting is doing the jobs I wanted to do but that doesnlt stop me wanting to learn a better and more economic way.

Cheers... make me feel good asking a question.

It's a slot across a piece of mild steel.. and a question as to possible methods to be tool sparing. Yeah if I had a hundred to do then doubtless something like a nice horizontal mill and wide cutter, flood coolant etc But this is reality for a hobbyist - Jeez!

Driving tools hard sounds good..I managed to burn one up - which wa fine as a learning experience of how hard i can push them - and I have no doubt that the more rigid, less vibration machinery will do a beter job..presumably also better grade of endmill. Or just send all ones parts away to be made and just bolt them together. or buy a finished product and don't bother...

Somewhere there has to be compromise and I was trying to learn

Sorry- forgot to give an example depth - say 15mm

OK I can see lots of ways of doing this - for this example a slot full width 50mm across and 30mm wide.

The question is about speed of getting it done and tool sparing.

So first option might be to plunge cut nibbles of say 3mm with a 12mm endmill and then tidy up sides and depth compared to slow side cutting with an endmill - would take lots of coolant and a v slow feed or say turning the part on it's side and chain drilling where one can and hand cutting the rest before endmill tidying. We'll ignore having some massive punch handy but I assume one could chisel it?

or how about modifying the grind on a fly cutter to be a bit more like a boring bar and progressively cut with that?

Doubtless there's other ways too.. but the question is best for tool economy (a fly cutter re grind easy enough or even ordinary twist dril sharpenings.. but endmills not so easy without jigs) and speed.....

..from humbrol's website: (the last time I used their paint was 52 years ago)

Paints

• Enamel Gloss Paints: Surface dry 1 - 2 hours, Fully dry in 24 hours
• Enamel Matt & Satin Paints: Surface dry 20-40 minutes, Fully dry in 24 hours
• Enamel Metallics: Fully dry in approx 10 days
• Acrylic paints: Fully dry in 1-2 hours, please allow longer for Gloss and Metallic finishes
• Acrylic Sprays: 15-30 minutes

Sprays

• Fluorescent Sprays: 15-30 minutes
• Multi-Effect Sprays: 15-30 minutes
• Metal Cote Sprays: 30-60 minutes
• Glass Etch: 15-30 minutes
• Crystal Clear: 15-30 minutes

Weathering

• Weathering Powders: Dependent on the application
• Enamel Wash 10-20 minutes

I've ground some according to 'toms techniques' youtube vids and they work OK.. and he cools his as do I (mine in a mix of collant wash). But it is tedious to do and frustrating if you bog up near the end. I've tried using my tormek wet wheel that i use for wood carving chisels but that really is slow. I've also used my belt sander but you can't get just the edge of the front of the tool at it properly without tripping over the belt sander;s own edges (as in the belt is a centimeter in).

I;ve just ordered a 60 grit diamond disc to try on the belt sanders disc face which has no rim. if that works then i;ll build a holder to sit on the platform there for compound angles. It was about a tenner on ebay from china so it'll be interesting to see what it's like.

As for the cooling argument.. well frankly I don't think that the difference between the heat needed to burn my pinkies and a dunk in room temp water is enough to matter - guesstimating a drop from less than 100C to 20C. And you can dunk before you start.

When I was still working for fine surgery (such as eyes) I bought a magnifying loupe. far from cheap with in-built illumination etc. They came with the option of prescription lenses but at that price if I'd gone that route then oter staff couldn't have used them. As my eyes got worse i had the local optician make up a simple pair of glasses for me.. the varifocal prescription I have with a flip-down second set of lenses to increase the magnification when needed. They work almost as well as the loupe,,cost about half and are actually lighter to wear (and eligible as a business expense)

The only thing to note is that suddenly adding high mag means that your distance judgment has to get used to that... don't go waving sharp stuff about until you've got the hang of it and your focal distanceis shortened a lot so you have to get used to keeping 'in range'

I use those lighter blow torches for soldering heavy duty copper wire into 5mm bullet connectors but I doubt they'ld cope with the thermal mass of your copper end caps.

This simple sole was wondering about modifying a cheapo variable speed electric drill for the purpose - to solve the issue of transformers and sourcing a matched potentiometer?

I bought one of the lidl 'parkside' compressors when I bought this farm. It was cheap enough (under £100) and quite apart from being invaluable for tractor tyre repairs, blowing out the chainsaw and running sanders and rust scalers it's small enough to park in the shed and blow rubbish off the mill and lathe. The tank's big enough that once it's filled itself I can turn it off and have enough air stored for swarfing ( switch on compressor, fire up laptop, light woodburner,put aay last night tools, switch off compressor). I;ve never used it for spraying but have no doubt that the right gun would be fine

Is that 4mm before or after refacing? What diameter?

A thought from a newbie: How about boring a centre hole out of a length of scrap ally, popping 2-3 1.5mm setcrews around the diameter to hold the work in there while you face and internally chamfer then drill a threaded hole inside the bar, to fix a truncated cone to clamp onto the internal chamfers and chamfer the outsides? Set screws will be reduncdant now and you can chamfer the fixture away.

There's a lot of double-sided tapes about. Id just hoped with my post that someone might have had experience wth a specific type for this sort of application. Or indeed with glur technologies. For a surface this large t's less a matter of adhesion as of side (shearing?) movement.

Something like the glue on post-it notes woud probbaly ahve done. For really strong adehsions then the stuff used to stick car bumpers on would be way efficient but might be a b*****r to remove. Mounting tapes and pads - well the padding will introduce some side movement..

I'll likely go with the screws. In fact since the square will be screwed on a frame on it's edges I can drill those holes before trephining and use them to mount - which this dumbo hadn't thought of before.

Ah! The screwheads idea I like..upgraded perhaps with some washers... saves wasting tape too <s>

I'll take a shot at that once the current job run is finished.

Thanks guys (again)

pgk

..also I can't sneak upn the diameter..

pgk