It's begun....

[Washout]

Hi all,

Since my last update I've been doing some research on feeds and speeds and trying to understand the relationship between the two (amongst all the other variables).

I've used GWizard and also FSWizard to compare results and tried to compare to the advice I've had and I certainly need to use 2 flute (or even single flute) cutters to bring the speeds and feeds down (ordered a bunch and they should be here Monday or Tuesday).

Also I am a bit mystified on one thing: HSS vs Carbide end mills - Carbide F/S results from the wizards above seem to be way way higher than HSS and I know that carbide is alot stiffer, but do the carbide end mills actually need to be run at the multiples higher than HSS given the same geometry should result in the same chip loading? Or is there some other factor I'm not grasping?

Off to try and make a mount for my airbrush/mister :-)

Cheers


Chris

[JAZZCNC]

Chris,

Just gone back and looked at the first post in this thread and I see the basic frame but can you post pics of the finished machine.?
Reason I ask is that you mention single screw and from the pic I'm thinking you must just have it down one side and not central to the gantry.? If I'm correct then your wasting your time using any calculator has the machine is so compromised with this set up they will be massively off target. Esp in aluminium.!!

EDIT: scrap that request looked a bit further up and found it.!! . . . Give it up untill you have the other screw you've no chance.!! It will turn into another beast with 2 screws.!!!

Looking at the machine and it's stubby size and strength then with twin screws it will easily cut aluminium with 3 flute cutter at 2.5mm DOC and 1500mm/min or more.
My machine is much wider and I easily cut at these figures and just today using 8mm size of this cutter (E5711 series) http://www.cutweltools.co.uk/files/ww/SM%20A160.pdf I was playing with DOC and cutting at 5mm Doc @900mm/min 9-10k rpm full slot without any trouble what so ever. I will try even deeper with 45% step over when pocketing and the tool spec says ok upto 1.5 dia @700mm/min 8K rpm.

HSS or carbide is mainly down to strength and the fact Carbide tends to work better when loaded up and can handle much greater heat and forces. To be honest I find I get better finish from HSS in Alu and actually prefer to use them for jobs where don't want to apply finish pass. With Carbide I can hog away put always have to do a finish pass for an acceptable finish.!

[Washout]

Yeah I figured the single x axis ballscrew was causing weakness - I'll get a mail over to Chai for a new ballscrew with appropriate machine end and go the pulley/belt route (seems less prone to error than two steppers). I'm looking at Zapp/Gary for the belt and pulleys if I can decipher what length belt to order (whether the length is for the whole belt or the loop if folded in half - if that makes sense).

As always thanks for the sage advice and assesment of the machine once its been upgraded (I like the sound of "beast" :-) ).

Chris

[JAZZCNC]

I'm looking at Zapp/Gary for the belt and pulleys if I can decipher what length belt to order (whether the length is for the whole belt or the loop if folded in half - if that makes sense).

Determine the screw centre distance and pulley pitch/number teeth then use a belt calculator (see attached) to find the number of teeth. (Or looped belt length) But if you order by number of teeth there's no room for error.!

The machine will be a beast at this size and strength. To give some idea my machine Y axis travel is 1100mm, so technically more likely to be weaker or more flexy than yours.
Smack bang in the centre at 3/4 Z extension so possible 120-130mm extension below Z axis. I've just cut a oval pocket 70mm x 30mm length single pass at 8mm Doc 45% step over @800mm/min 12Krpm in 6082 T6 Aluminium just using blown air no misting or coolant(quick initial squirt of WD40).
In doing this, it first spiralled down to depth, it then had to cut full slot for about 40mm and while it moaned slightly more than the when cutting 45% stepover it still handled it no problem and the actual 45% stepover was a doddle and I'm sure I could have easily pocketed at 45% step the full 10mm depth of material.

While bit extreme on DOC and not something I do often at full slot width. I Can't see why your machine couldn't do this kind of cutting and like mine will most certainly easily handle half this DOC at higher feeds.

[Washout]

Wow, if I get half that performance I'll be ecstatic :-)

Thanks for the tool - that's a great help.

Now to see if I can get a ballscrew macined and delivered before Christmas.....

Chris

[Washout]

A quick pic of the machine for those interested.

Doesn't look like I can get a ballscrew machined before Christmas, so the build/upgrade etc is going to have to go on hold. I'm also moving house next week, which means taking the gantry off or seeing the removal guys slip a disc or two and this will also be a good opportunity to fit the second ballscrew when it arrives.

For the sharper eyed amongst you I didn't have my new gantry mounting brackets on when I took this pic, but they are ready. Also for some reason the flash on my crappy camera phone has made the ali extrusion look like I have pimped it with blue LEDs, but the coolant is indeed green. I've been using PC watercooling pump and fluid, as I have been water-cooling my PC's for years without any gunk forming and using a spare radiator/fan unit means I don't need much of a resevoir for water. So far I've yet to feel my spindle get warm after a continuous 54min session.

BTW - the new house has a 31x15 foot workshop and I'm going to be building a workbench down one wall out of steel box section, which means learning to MIG weld - does anyone have any recommendations for a welder and whether gasless or gas is better?

Cheers


Chris

[JAZZCNC]

BTW - the new house has a 31x15 foot workshop and I'm going to be building a workbench down one wall out of steel box section, which means learning to MIG weld - does anyone have any recommendations for a welder and whether gasless or gas is better?

Gas less is mickey mouse stay away if you want to weld seriously. If your mainly going to weld box section or thicker stuff then just buy a cheap stick welder because to weld 3mm box section you'll need a decent sized Mig. . . . Cheap Migs are rubbish and pretty much useless for thick stuff.

Also to get decent welds from a Mig you wan't CO2/Argon mix (Boc Argo sheild) and the little cannister bottles and regulators that usually used with cheap Migs are rubbish/expensive and last about 40mins on a good day.!! Plain CO2 or pub gas spits like crazy.
The real Mcoy bottles are difficult to get hold of unless you know somebody with an account at Gas supplier and even then you'll have to pay for the bottle rental plus Gas.!!

Even the cheapist stick welder will give better welds in 3mm box than an average power Mig.!!

[AdCNC]

For the sharper eyed amongst you I didn't have my new gantry mounting brackets on when I took this pic

First thing i looked for.

Id go with Jazz's recommendations, i was in the same boat as to what welder to go for a few years back and last year i bought a old oxford oil filled welder off e-bay probably the best arc welders you can buy IMO. then from there i got a new Oxford S-Mig 330-1 even tho the new Oxfords are not made by Oxford but Technical Arc. They are very good welders, and for the money even the cheaper ones they do will be good.

But id look on e-bay for a old oil filled arc before you get a cheap buzz box arc welder!

[D.C.]

Got to agree with Jazz that arc is much better than mig for this sort of thing.

Something you may want to consider is having a look on the skill swop websites to see if you can find someone local offering free welding or just find someone that you can pay to do the one off welding job for you. They will probably do a much better job in a couple of hours for beer money, so if you only have this one job that needs welding it might be a lot cheaper and easier to outsource it.

Buying your own welder even second hand, some sticks, gloves and a mask mean you are probably going to drop £50 - £150 on gear easily and then you will spend hours researching how to use the thing, hours practicing and then do a not great job of welding the frame.

Of course if you want to learn to weld and have lots of ideas for projects that need welding, it's lots of fun and very satisfying so go for it! :)

[Washout]

Thanks guys,

I'll do a little more research before settling on something, but I'd like to learn the skill myself, as there will be other projects that require it (I need other sturdy work surfaces run up for example).

I was initially looking at MIG, as it seemed the easiest to pick up and from a few tutorials I have seen looks to be a matter of timing and motions to get a penetrating and consistent weld, but like decent soldering (or any other skill for that matter) will be a matter of practise, practise and more practise I expect.

Thanks again


Chris