Tools don't snap when you plunge, everything will want to vibrate when you plunge but not break. They usually break when your aluminium starts extruding, when you accidentally G zero in to the side of the billet and for no reason at all whenever it is most inconvenient. You might expect them to go flying off like rifle bullets heading straight for your eyeballs, but they actually just drop right where they are. It's weird.
Cutting forces are probably greatest when slotting. If you have enough power to snap the tool you cannot use any more.
Of course you hardly need any power at all for rapd transits because there is no cutting force required. You adjust the accelerations/decellerations to allow for the gantry inertia.
Originally Posted by BuildingAfloat
Originally Posted by BuildingAfloat
Ok lets get this out of the way
Ok this is really hard for me to write, I have to say what I have to say or I will have to stop posting. Without going into too many details, it has taken me a tremendous effort to post what I have posted so far. Lets just say, that if things had gone differently on the 2 days leading upto my first post, I may not have made my introduction ever, let alone any subsequent posts.
When I say I am struggling with overload, I really am, with every new bit of information I find it harder to see a way forward with this project. I never used to be like this, having a label and a knowledge that it is a bit of chemical imbalance does help, but I don't really understand how or why it fecks me up this way, So I don't expect you guys to.
I don't want to sound ungrateful or ignorant and all previous advice is stored for when I am better able to deal with it.
So how do I move forward?
I really need some structure to this, so I think what I will do, is start at the cutter tip or rather the router itself and work backwards as that is the way I have worked when designing the first draft of the machine, not sure if this is odd, but hey ho! I will explain my reasoning as to how each decision was made.
Given I want to build a machine witin the pillar drill only build parameters, how can you help?
Well for a start, please bear with me and let me go through this bit by bit. If I set the pace I'll get there in the end.
If at any point my reasoning is dangerous, completely flawed or the machine cannot work because of it, please tell me! I will then ask for more help to fix that area.
I have tried to find the best prices in the UK and EU primarily for the bits to build this, nothing against the ROTW, just a preference for supporting the local guy. After much hard thought I am going to go for Ballscrews will have to redesign accordingly. Since you all seem to buy from Chai (?) and all seem happy with him, it makes sense for me to do the same. Any help in beating the prices I've found would be gratefully received. Second hand is not at ruled out, neither is eBay if I can beat you lot to the bargins :-) Free, while being awesome is not what I am expecting here. I want to pay my way properly or be able to at least help someone, somewhere in exchange for goods if they are FOC, even if it is not the supplier directly and I will of course want to pay P&P. Not Karma exactly, but I'm not after a free ride either.
In an ideal world I'd have all the cash together before I start the build, but unless I am very lucky this won't happen. This is a very vague hope, but I guess I am looking for a strategy to make this peicemeal gathering of the stuff at least bearable.
Since there are flimsier (flimsyer ? No that looks worse!) machines out there and no one has shouted "No! don't do it, it is a complete disaster" I guess I am at least the right ballpark for a working machine.
Ok to support my choice and ambitions, Amongs the dozens of videos of machines in action, this video of a Heiz S series machine Milling In Steel caught my attention. These machines are neither the gruntiest or the sturdiest out there, but here is one cutting steel at what to me is a totally acceptable pace - I couldn't do it with a fret saw or jig saw at that speed or accuracy, so I would be very very happy with this as an absolute peak of my ambitions for this machine. It hasn't got to do it all day, every day. Just be able to do it occaisionally. The speed accuracy and finish are not critical on any material, I want to be making more artistic stuff than I do engineering components and a bit of hand finishing is a lot better than a lot of hand cutting.
I started with a combination of the Heiz & Marchant Dice type constructions running through my head and I hope I have come up with a machine that is stronger than either. I also hope to be able to get it completely built with enough software to make useful stuff for around £1500.
I'd now like to see how close I can get to these goals with my comstruction restrictions and you step by step guidance.
Item 1 - Spindle Choice:
Worst case: Use the router I already have - this is not much more than a single speed noisey toy - Ruled out as non-starter!
The ideal: A water-cooled, fully speed controlled auto-tool-changing spindle! - Ruled out as I had to stop somewhere!
Model: Kress FME1050-1 High speed spindle
Volts: 240V with IEC connector
Spindle speed: 5000 to 25000 rpm
Power: 1050 Watts
Reasons for choice:
1) These seem to be the aircooled router of choice, CNC-STEP, Marchant Dice and
countless home builds use them.
2) It's the gruntiest one they do. At least as far as I know.
& 3) I liked the wide speed range it offered, since I will be machining mostly wood
and I want to have a go at machining Brass, Aluminium and sheet Steel, its relatively
low speed capability appealed to me as it must be a help when it comes to metal
Model Engineer's Digital Workshop
Price: £168 inc VAT - This was the best price I could find
One question: Is this the best value for money I can get for an air-cooled router?
Sorry for the length of posts, it is just where I am atm.
Last edited by mocha; 02-08-2012 at 11:46 PM.
I cannot reccomend using a Kress router for cutting metals - in the end it's still a router not a spindle. Whilst clearly from the video you linked to it is possible to cut metals with it, that's not really saying much on it's own. You could cut what they did in the video with a hand file, but that doesn't mean it's a sensible method. One thing you don't get from videos is the impact on the life of the tool, which is important here since that is putting a high force onto the Kress' relatively small bearings, which will have a detrimental effect on their life. One often sees videos where people are pushing the machine or tool too far, maybe it works, but if the video lasts 2 minutes and the tool only lasts 5 minutes at that speed then the video is misleading.
Much better would be to get one of the water cooled 2.2kW spindles from China that you've no doubt seen in other build logs. Among other things they have much higher rigidity and lower runout than any router, including the Kress. For cutting steel you need quite high torque at a low rpm, which is something most high speed spindles and routers lack, but to an extent you can get away with it by using small carbide tooling ideally with the right coating.
The obvious problem is you're in a similar situation to me when I starting building the router - it needed to be cheap as otherwise I couldn't make it. For that reason alone I started off by using a router for about £6 from the local car boot sale. It was fine for cutting wood at a modest speed, but no chance of cutting metal properly. After (approximately) a few months I did break it by being a bit too ambitious with the tool length, but by then I'd done enough with it to persuade the 'Bank of Mum' that it was worth getting a better spindle, so after a similar discussion on the forum I got the 2.2kW water cooled spindle. The difference in performance is huge.
So basically I think you should try a very cheap router to start with as that'll be fine for making signs and other bits of pieces from wood, then you can re-invest the profits in getting a proper spindle and start cutting metals. Unlike the rest of the machine you don't loose much money by going for the very cheap option to start with and still have a useable machine.
03-08-2012 #25So basically I think you should try a very cheap router to start with as that'll be fine for making signs and other bits of pieces from wood, then you can re-invest the profits in getting a proper spindle and start cutting metals. Unlike the rest of the machine you don't loose much money by going for the very cheap option to start with and still have a useable machine.
I completely agree with Jonathan regards the spindle VS router but would also like to point out one other advantage the WC spindles have over router based machines and IMO it's significant esp for some work like V Carving and 3D work.? . . . DUTY CYCLE.
The cheap BQ £30-40 jobs have a duty cycle about the same has chocolate in sun shine.!! The better Kress routers claim about 8hrs Thou I very much doubt they will do too it many times before showing the affects.?
When cutting decorative type work, esp things like litho-pains and 3D carvings then the cutting times can easily run into 12+hours and far longer if large sizes.
The WC spindles can run 12hrs without batting an eye lid and it's not unusual for me to leave mine running none stop for 20+hrs.!!
I know we all want to keep costs down but some times your far better off waiting an extra few weeks or months to find the extra money. When the difference gets close like with the Kress VS WC spindles then it really does become worth the wait has they don't compare to each other. Like Dean says your CNC experience will be so much more pleasant and rewarding not to mention in the long run far cheaper.!!
Thank you Jonathan, Deanos & Jazz,
I agree totally, however I cannot use "best practice" for this machine, every upgraded component drives the cost up and makes this machine more and more unlikely to happen!
Sorry for yet another long (and in the end somewhat contradictory) post!
I had hoped that between my introduction and the "Information Overload" post I had made my situation clear, I think I have missed something, I'll have another go.
I'll relate my CNC desires to cars and motorcycles to give you an idea of my needs...
Scale Cars Motorcycles CNC Dream Lotus Elise Full hand built custom Servo Motors, Water-cooling
No compromise frame 8x4 cutting area
Best I've ever managed Second hand Alfa Romeo 1600 Twin Spark Moto Guzzi 1100i Jackal This construction of machine with Water-cooling and ballscrews. Reality Now! Skoda Fun Pickup
"Jack of all Trades"
Had to sell it, but last bike XJ650 Yamaha - "Jack of all Trades" This build
"Jack of all Trades"
Unacceptable Beat up Opel Corsa Beat up old CB500 Honda twin "All tread", gas pipe, skate bearing
This table shows a "Law of Diminishing returns"
At the bottom, things are cheap but barely functional and you'd soon be cursing them.
At the top, and certainly on paper they are better than everything else, but their price and true performance envelopes are beyond me and most likely always will be!
My aspirations are for the 2nd level, a bit better than I really need, but with a bit of a spare capacity for pushing MY limits, but not so much they are too scary for mundane tasks.
Where I am, the top of the performance envelope is still really enough for my needs, but I appreciate the margin for error is much reduced. However I accept this, as in everyday use, the "Jack of all Trades" does most of what I ever really need.
The aim is for the machine to be more capable than the entry level machines (such as say the Heiz S400) and around £500* less in total build cost. As I tried to say in the "Information Overload" post:
I need to know that this design will not self destruct and I have found the best value for money for a given component. Or for a given budget (assume I am really maxXxed out with the prices I will give) is there something better?
*I have a final figure if £1500 in mind, this is already 50% more than I can really justify at the moment, I have seen the "think of a figure and double it" in many more places than this. However, I have priced everything I have added to the drawing and virtually all the control components and still have a bit of space to breathe in this figure.
I have £410 to spend at the moment, my goal is to come out of this discussion with a set of plans for a scaleable machine that will most importantly, work and that I could sell to help fund the rest of the build. That will be hard I know, but it is not impossible. There have been plenty of "crowd funded" CNC machines in the USA, so why not one in the UK? I also plan to offer upgrade drawings using the machine to make its own upgraded components - see later posts!
Most of the plans I have found are for MDF and other wooden structures. I have found only one set of plans for an extrusion based machine, so I hope there will be space for me to sell some of mine, I can't be the only one thinking MDF is not really the material for a such a machine!
I am taking responsibilty for the path I am taking, I know you want to help me by suggesting that I spend just a bit more money you won't regret it, I can see that totally and it is excellent advice, but I am spending 50% more than I can really justify and planning on spending over 200% more than I actually have already!!!
So at the risk of upsetting you all, please just help me by answering the direct questions I ask and keep the "If onlys" for another day, when I am more able to keep up with them and do something about them.
OK one last Kress vs Watercooled, the following is based on my findings for the WC spindle, I'll be asking questions at the end, so please pay attention as many a teacher has said!
Kress Watercooled & VFD Min Speed rpm 5000 8000 £ Just under £170 Best I found £250 Additional cost excluding cutters and collets £0 Pump, tubes and a bucket! Say £20
Ok so £100 isn't a lot, but it is 4 stepper motors! Which may be enough to save this project.
Mmm why does the brain work and find solutions from advice while writing posts? Not going to re-write so please prepare to laugh while I shoot my self in the foot!
OK, my strategy is going to be as follows:
1) Original aim was to use Kress, many people including me are happy with these, so I will keep that possibility in the plans. A wider router clamp for the WS Spindle still allows for this so Win/Win!
2) Get drawings for WC Spindle as at 80mm I will need to draw a new Z axis to make space anyway. Downside is a few more millimeters will have to be pinched from an already less than ideal final travel on X&Y (Although I can scale each axis up, I have space constraints to work in).
3) See if I can find my old hand-held router and measure it up, from memory it may be bigger than the WC spindle, so to use it I will need the redraw anyway!
4) Whatever happens, use said router in the CNC machine to start making stuff, £170 less to find to get going and aim for WC Spindle, if it breaks before I'll try and have to find the rest!
Questions needing answers:
1) Does anyone know of a better price for the Kress than I posted earlier?
2) For the price of the Kress, can anything beat it?
3) Bearing in mind and forgive me if I am wrong, a reason given against the Kress and in favour of the Spindle was on the grounds of speed (See table above as to why I am asking this question) How do you bring the WS Spindle speed below 8000rpm?
4) What equipment is involved in the solution to 3?
5) Where is the best place to buy solution 4) and the WC Spindle?
6) Does anyone have the Drawings for the WC Spindle in 5)?
7) Can you advise how best to mount the Spindle in 6)?
I think that is all I need to ask for the router....
& finally 8) I'd love to see more extrusion based plans, in order to evaluate them for later what have you guys found?
just something to consider on your router vs spindle cost, i'm pretty sure i saw someone recently buy the cheap chinese spindle that johnathan and jazz talk about for the same price your looking to pay for your router.. if i can remember where i saw the post i'll come back and link it for you
The Following User Says Thank You to wilfy For This Useful Post:
WATER-COOLED MOTOR SPINDLE 1.5KW + MATCHING INVERTER f4 | eBay
here we go.. i dont know enough about spindles yet to know if it's a good one or not, but my point is there seems to be a fair bit of choice around your price point for a longer lasting W/C spindle
Why exclude collets in the comparison? The price of the Kress collets is huge compared to the ER20 collets for the spindle if bought in China. Clearly it depends how many different size tools you end up using, but if it's a fair few the price difference wont be so great...
I don't see the point of 1) and 2) since if you use a very cheap router to start with (suggest going to car boot if there's one near you and getting a variable speed one) you wont need to buy a Kress.
3) I've used the WC spindle at 5000rpm to drill aluminium with a 4mm drill, so although the torque is limited at that speed there's still enough to be useful.
4) It's just a matter of tweaking the settings on the VFD and having good cooling. Although it helps to buy a better (more expensive) VFD.
7) Here's one or two I made earlier:
I'd advise using 1/2" thick aluminium.