Or perhaps to the motion control board (driver) .. CliveQuote:
Originally Posted by EddyCurrent
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Or perhaps to the motion control board (driver) .. CliveQuote:
Originally Posted by EddyCurrent
Clive, sorry I'm not sure what you mean ?Quote:
Originally Posted by Clive S
To clarify, by driver I meant motion control board. Feedback should go to that and not via the bob.
You are 100% correct of course, I was just trying to differentiate between a simple BOB and a full blown motion controller (driver) type.Quote:
Originally Posted by EddyCurrent
Sorry for any confusion. ..Clive
I thought I'd had too many 'old speckled hens' :beer:Quote:
Originally Posted by Clive S
There's actually a lot of debate on this topic when using LinuxCNC. Since LinuxCNC is real-time, you can implement the PID controller within the computer (instead of the motor drive), and have the computer output speed instead of position (step/dir) signals. That can work well, especially if you use a PCI card. Some people consider that better as then the computer is always tracking the following error... but just saying that is really oversimplifying the situation so if interested, Google it.Quote:
Originally Posted by EddyCurrent
After reading these days a lot of motion control manuals, i think i have it more clear. The majority of them have their own brand daughter boards and that's the main reason it seems that they can close the loop directly on the board, for servos and steppers. Also most of the expensive ones have possibility to input 2 encoder signals on 1 axis, so they can control backslash this way. Also it seems connected to some external servo drives, even if the servo drive closes the loop, it can transmit it to the board at the same time, for the previous reason or for some extra functions.
Now i just cant believe how little choice there is for 5 and up axis BOBs and combinations, especially to work with mach3. I almost discarded the Galil. Read in forums there is no support at all if you don't buy it new. Which is crazy for a product that is worth thousands. Also 99% at ebay sell them on As Is basis, but not for As Is money. I dont see my self paying hard earned cash for a board that is not guaranteed at least a week from the sale. Also read that many of them are possibly tweaked for a certain customer, so even less support. And later to have problems with the Mach3 plugin...I was tempted. And still i am.
Its unbelievable how poor the choice of BOB is today. Couldn't be that more clear what is needed:
-USB or Ethernet board,small sized, mach3 plugin, on board spindle control, on board 220AC/transformer, opto isolated inputs and outputs, 6-8 axis,4 relays,...
Combining all of these is almost impossible and starts to get expensive. Same price as second hand motion controller :soap:
Silyavski, I know this is not what you are after but may be of use.
Got one of these the other day, great little unit and great price.
5V 1/2/4/8 12V 16 Channel Relay Module W/ LED Indicator Light For Arduino | eBay
also these spindle boards work good and not too high a price
System4
If you don't need slaved motors and using steppers then have a look at the Csmio-IP-M controller or the Csmio-IP-S if you need slaved motors or using Servos with high count encoders and want the full package. Here CS-Lab - CSMIO - CNC Ethernet Controllers- inexpensive solutions - CS-Lab CNC controllers CNC Machining CNC software.Quote:
Originally Posted by silyavski
They are very high quality Ethernet Motion control units with industry standard 24V differential digital I/O so very good at handling electrical noise also come with very High quality Analogue spindle output built in. (Sorry to say this Eddy but those Spindle 4 boards are very erratic with speeds jumping around all over the place, used a couple now and not impressed.:thumbdown:)
No BOB or external Spindle board is needed all mounts on industry Standard Din rail with separate quality Din rail connectors. Simple to fit and install plus very very neat.
I've used just about every Motion control card now in the Diy range so Sub £300 and I can tell you 100% these knock the spots off any other.
I've fitted 2 now but only on new build machines so couldn't compare same machine performance against other Cards but unfortunately and very very frustratingly for ME that's just changed.!!
The Russian PLCM E3P I've been using on my own machine has just gone faulty, doing strange things and tripping with noise issues from VFD, either using USB or Ethernet connections.
Couldn't have happened at worse time has I've been flat out chasing my arse between Family health issues and getting stuff done plus now every where is closed for Xmas. Just lent my spare ESS smooth stepper to a friend who isn't answering his bloody phone, just sold the spare spare USB SS has never used it. . Arghhhh . .(PLCM E3P is now smashed into 1,0000000000000 bits.!!! and NO it gave me no satisfaction other than to vent.!)
No way was I going back to Parallel port, plus laptop doesn't have PP. So I've got Csmio-IP-M which was half fitted into a control box destined for machine currently !!.Trying.!! to finish but needs must so out it came temporarily until I can get another Card.
WOW . . . 20mins later it's wired up, software installed and working with full spindle control.
Worked Straight off Copy of my Old Mach3 profile with just a quick Plug-in swap and pin assignments with very little tweaking of motor tuning required. . . In fact this is what really impressed me has now can tune the motors much higher even thou the PLCM-E3P and CSMIO_IP_M are both supposed to be 100Khz.
I haven't had or got much time to play and don't need the speed anyway but the first dabble took my My Y axis from Max 11mtr/min & 950s/s Accel to stable 14Mtr/min at 1200s/s and that's with 5mm pitch screw direct drive on 3.5Nm Nema 34 motor at 75v. That's 2800Rpm from Nema 34 motor.!!!. . I was quite impressed with 2200rpm the PLCM allowed.!!
The Motors so sound very sweet even at these dizzy heights and the pulses are clearly very smooth has the movement is excellent even at very low feeds.
Wouldn't ever run at that speed has I don't need it but it just shows not all Cards are Equal and I'm positive this speed increase is down to the quality of the product has it's the only thing that has changed on my machine.! . . .Very impressive and I won't be coming off any time soon so I better get another ordered ASAP.
. . . . . HAPPY NEW YEAR EVERYONE. . . .Keep smiling.:yahoo:
Lately spend too much time on choosing the BOB, motors and drives, which delayed my order for the ball screws and the rails. After all that talk, last night saw 2 interesting Galil listings on fleabay and something made me push the button and send best offer, thinking that if one accepts, will cancel the offer to the other.
Well, after i woke up this morning i found my self the happy future owner of 2 galil BOBs. i thought of excusing myself to one of them, then decided and payed them both. With the idea if one not working to use the other, or at least to see which one i like best. the other goes later for next machine or whatever.
So i bought the GALIL DMC-1880 PCI 8 axis Optima motion controller and the Galil DMC-2183 Ethernet/RS232 8-Axis Motion Controllers & 2 ICM-20105 Opto I/O .
Both seem to work with the Mach3 plugin / yes i checked before sending the offers/ .
I have some feeling that i made the right decision with these. What do you think?
Now i have to decide on the drives and motors. First of all now i can run steppers with encoder and servo motors directly closing the loop at the motion controller. Which in fact can lower the price of the build, implementing servos only for moving the gantry and steppers on the Z if i decide so.
No i am looking at a Galil AMP-19540 at ebay which coul drive directly 4 dc servos up to 500w each, costs only 100euro and connects directly to one of the BOBs i bought - the DMC-1880 . It seems this purchace can save me a lot of money on other drives and cheapen considerably the project, sourcing only the motors.
However i understand nothing of these type of servo and drives for me the description is like Chinese, i only see 500W :-) , here is from the description:
Quote:
Galil's AMP-19540 is a 4-axis amplifier for driving brush or brushless motors up to 500 Watts. By interfacing directly to Galil's DMC-18x2, DMC-18x0, or DMC-18x6 controllers, it provides a cost-effective controller/drive solution for multi-axis applications. The AMP-19540 contains four transconductance, PWM amplifiers for driving brush or brushless motors. Each amplifier operates at 18V to 80V dc, up to 7 Amps continuous, 10 Amps peak. The AMP-19540 gain setting is easily configured with jumpers. The PWM switching frequency is 60 kHz.
Quote:
The AMP-19520/40 is a brush/brushless trans-conductance PWM amplifier. The amplifier operates in torque mode and will output a motor current proportional to the command signal input.
Input Voltage: 18-80 VDC
Continuous Current: 7 amps
Peak Current 10 amps
Amplifier Gain 0.4, 0.7, or 1.0 A/V (jumper adjustable)
Switching Frequency 60 kHz (up to 175 kHz available--contact Galil)
Minimum Load Inductance 0.5 mH (low inductance option available)
Communtation Angle 120o (60o option available)
So, can some one help here please:
Can i find easily BLDC motors suitable for the drives, with hall sensors as far as i understood, new from ali express or from ebay? Are these drives any good, mean in 2014? And for my build?
Thanks Eddie,Quote:
Originally Posted by EddyCurrent
I will grab one of these, just have to figure how many relays i need.
Now that i have bought the Galil 1880 and have only 1 x 100 pin cable going out of it, i have to fashion something like a terminal breakout board where to connect all the I/O signals.
Any idea what cheapo components will fit best together? I am a bit lost here and dont have the money to buy the galil I/0 board. The connecting cable it seems is SCSI 100-Pin High-Density connector, though not completely sure.
Here below are some specs from the manual of the motion control/ Chapter 3 Connecting Hardware/ :
The DMC-1700/1800 provides optoisolated digital inputs for forward limit, reverse limit, home, and abort signals. The controller also has 8 optoisolated, uncommitted inputs (for general use) as well as 8 TTL outputs and 8 analog inputs configured for voltages between +/- 10 volts. 1X80 Controllers with 5 or more axes have 16 optoisolated uncommitted inputs, 8 TTL inputs, and 16 TTL outputs.
Wiring the Optoisolated Inputs Bi-Directional Capability. All inputs can be used as active high or low - If you are using an isolated power supply you can connect +5V to INCOM or supply the isolated ground to INCOM. Connecting +5V to INCOM configures the inputs for active low. Connecting ground to INCOM configures the inputs for active high. INCOM can be located on the DMC-1700/1800 directly or on the ICM-1900 or AMP-19X0. The jumper is labeled INCOM. ....
From what i understand everything important is opto isolated. The servos i bought seem to accept various signals, still have to fight with the manual to translate things like:
Position command can correspond to the following four types of output form.
Line Driver Output
+5V Open Collector Output
+12V Open Collector Output
+24V Open Collector Output
- Line drive output may correspond up to 450 kpps, and open collector output may
correspond up to 200 kpps.
It seems that the drives accept 5v signal, but recommend external resistor and 24v signal, for interference resistance.
Still have to figure what is line drive and what is position command, it seems to me line drive could be step and direction ans position command should be differential signal.
Post up a link to the servo manual and we may be able to give more guidance
Thanks!
I discarded the Chinese servos due to some worry that will be difficult to tune. Decided on Mitsubishi servos with very good specs, from fleabay. But could not find a good looking ones, or were expensive/ yeah, sellers know/, or were incompatible with mach3 /again sellers know and try to fry you/ .
Yesterday i payed for 4x SAMSUNG SERVO MOTOR DRIVER CSDJ-04BX2 and CSMT-04BB1ANT3 motor 400W. Absolute encoders 2500, auto tuning, max 450khz pps, in and out encoder signals, and so on.
Here is the manual:http://www.cnczone.ru/forums/index.p...e=post&id=8233 section6.1 and on
my head hurts from reading 10 different servo manuals :-)
Hi, long time i put this off, but now that successfully finished my first build i am back on the track with my machine build.
Now i have all the electronics, motors and major part/linear rails and ball screws/ sleeping at my garage. This time i will build it much faster.
Having learned a lot from the first build, i reconsidered many things and am trying to finalize the drawing stage, so i can buy the steel profiles next week.
Many changes were done, simplifying, strengthening and all this having in mind the common materials here in Spain.
1. Decided that the machine will be on no long legs. It will rest on the floor.
the benefits:
-I work alone so lifting heavy materials will be a problem in the future. As it will be multi functional, there will be removable plasma torch and 1000x1000x100mm removable water bed also, for the not so rare cases i need some parts from steel done until i make my self proper plasma table.
This is how it will look:
Attachment 12893
2. I wanted to avoid as much as possible laser cut pieces/$$$/ and use instead the profiles themselves as i would do the cutting at home which saves me quite a lot in fact. Only 3 types of steel will be used-100x100x4/the darker ones/, 100x100x3/ the lighter gray/ and 60x60x4/ the gantry verticals and reinforcement pieces/
The gantry support legs from 100x100x4 / so i can reach and screw the HIWIN blocks to the plate/:
Attachment 12894 Attachment 12895
The ball screw end supports from 2 pieces of UPN100 soldered together. I have the believe that this part is very important to be extremely sturdy in all directions as there wil be very heavy pull there, starting from the tightening and later when the gantry accelerates and so. Additional 2 100mm thick plates for reinforcement,one bellow and one for the face of the beam, so there will be no further doubt there :-).
Attachment 12896
3. The rotating ball screw nut
Attached to 10m steel plate via screws , the plate is soldered directly to the gantry sides. I couldn't help and add 2 ribs to the plate, just in any case.
Attachment 12897
basically the 30T HTD 5 pulleys are 90mm center to center, so 330m belt will fit according to this calculator http://www.bbman.com/catalog/belt-le...alculator.html
The problem here is that the servomotors have much larger central cylindrical part, so there is no more that +-3mm up and down for adjustment. that means the calc has to be very exact with servo motor, as oposed to steppers where i achieved +-6mm adjustment in both directions.
Attachment 12904
The other thing is that i can not find Alu pulleys HTD5 30t. Only steel, i am not sure but it could impact the inertia as its 3 times more heavy.
4. Back to the gantry. In a way i am proud of it :joker:
Now the gantry is where i took liberties with the design, hopefully for good. As i said before there is extremely small overhang. Unluckily there was no 120x100 profile available, though when i started the drawing they said that there is . So i redesigned it again. 100x100x4 and 60x60x4. As i started the gantry from scratch and put a lot of thought in there, i believe it will not only be very successful but in the future will serve as an inspiration to all that want the benefit of closed aluminum gantry but don't have the means or money and go with steel. I mean - take away half of the reinforcements and vertical reinforcements /remember-i will mount impact hammer/ , and it still will be heavy duty normal gantry, couple this with the gantry sides like i did them, and you will have cheap very nice gantry that you need a way to cut the profile and solder +2 plates for the HIwins.
In short I believe that's the ideal High Heavy Duty DIY gantry. I hope you will like the design idea. Hidden and short screw, motor inside, all cut from profiles including the sides. In a normal HD variant, there will be less vertical profiles, less support triangles and one less profile each side of the gantry sides.
Attachment 12898 Attachment 12899
FYI : On this picture bellow you can see that the distance i left from front to the vertical supports is 100x100 -60x60/inside verticall supports/ = 40mm. But if the ball screw supports have to be mounted on the vertical bars, no additional plates as i made them, then the distance must be 43mm. Even so the vertical supports will protrude at the back only 3mm which can be masked by soldering, so 100x100 and 60x60 is ideal combination for HD Gantry
Attachment 12900
This is how i envision a normal HD gantry, that will be comparatively very light for what it is and no need to go in the servo territory. I would like to hear critics or opinions on this :-):
Attachment 12901 Attachment 12902 Attachment 12903
5. The Z
This is on what i am checking and working today. have to check again if the cheese holes are right on spot.
As i said above, with servos i can not design a plate with more than 3mm of movement in both directions to tighten the belt. So i had to do something i dont like and split the Z motor plate to be able to additionally adjust the belt. Still have to calculate again the exact length. And so the days go by...
Will update the Z pictures, when i finish counting cheese holes :-)
Attachment 12905
6. The machine bed
Some changes here. Instead of vertically soldering 3 x 2 /100x100x3/ profiles i decided to lay them all in one plane, so the distances between them are very small-200mm. So the bed is really strong, even using cheap bed material.
Attachment 12906
Quite a long post, but i am excited :butterfly:
Hi Silyavaski
You have been busy with CAD, nice drawings, what cad package are you using?.
And great to see you have assembled the parts and drives....
How do you intend to join all the steel sections and the vertical bracing? By welding?
-
From memory you are going to use this machine with an impact hammer to make musical instruments.
-
Will it be an air operated hammer similar to one of these? https://www.google.com.au/search?q=a...w=1215&bih=817
-
I was using a small one hand one last week to break up some concrete. they cam deliver quite a blow, You can turn them down by using both a pressure and flow regulator. the settings will depend on what sort of material you are acting upon. even at a low setting the energy released is significant.
-
Tubular steel is very strong no doubt, however it can vibrate, particularly if the hammer is set to oscillate near the resonant frequency of the frame. Without very sophisticated FEA software it is hard to conceptualise just how a structure will behave. however you may find it advantages to consider the issues involved in advance and if vibration turns out to be a problem have a means of increasing the mass of the structure and what sort of damping measures you take to reduce the amplitude to an acceptable level.
.
Here is a link to an excellent paper on concrete filled steel structures used in machine design. http://www.mech.utah.edu/~bamberg/re...e%20Design.pdf
-
Regards
John
Hi,
Now the question of the day is having in mind all the servos are 400w, do I drive all 1:1 or 2:1 ??? The x y encoders are 2048 and the z is 2500 ppr ,all the screws are xx10 and 1605 for the z
The servos will accept 100000 pps at step mode
Last revision. Can not find a weak spot that is not bombproof. Starts to look more and more like a mill :frog:.
1. Decided to drivel all 20:30t, only the Z is 20:20t. This after exausting 3 day calculations, belt lengths,inertia, tooth engagement, speeds, etc. and at the end -common sense.
This is a separate thread of its own. I believe this the wisest decision between speed, acceleration, precision.
2.I decided to redesign the Z as it bothered me, especially with this long 1400mm belt. At the end common sense also helped here. At the end raised a bit the overhang without compromising anything so much. I design like this-until i see perfection at every detail.
So the Z. Tried to design it like a Russian tank from WW2. All plates are 20mm Aluminum.
- it would be covered against dust from all sides
Attachment 13068 Attachment 13069
-The cheese :hysterical: . The additional holes at the front are for mounting extra things, like: 3D plastic head, plasma torch, engraver, light and so on. The front plate on the moving box is separated in 3 parts. The lowest one is for the case when a so high object is machined that the spindle has to be all in, hence from there access to the nut of the spindle. the second part allows exchange of the spindle. The upper one stays there forever.
Attachment 13070
-The linear movement and where is placed. I even decided against using it for the hammer. the idea of making a precision machine and the trying to brake it seems less and less attractive. So this one will make the other which will be purpose build 5-6 axis, but anyways as i have 2 ball screws i decided to fit them.
Attachment 13071 Attachment 13072 Attachment 13073
-Reinforced the motor plate, this will hold the drag chain too. The belt now is very short as i like it, no extra pulleys and 6-7 teeth engagement each ball screw pulley. So seems ok to me.
Attachment 13074
The rotating ball nut assembly. 20:30t hence 1.5:1 driven. Compromise due to common sense. At the end precision and power at the same time is the aim.
2048 encoder on the motor, so more or less 20m/min. I see on the motor specs that it can go up to 4500rpm, just the curve is straight till 3000rpm. The resolution will be ~0.003mm on all axis , 0.001mm on the Z/ 1605 screw and 2500ppr encoder/. That without any artificial gearing or micro stepping which is not needed it seems. Thats good, cause the Galil board is not micro stepping board.
Attachment 13075 Attachment 13076
Quote:
Originally Posted by John McNamara
Thanks for the link.
Here is the comparison picture with the 3.2kw spindle. It weights next to nothing, compared to the spindle, which is a monster.
Attachment 13083
here i started to put the electronics together. No power cable in front, all go back shielded by the alu plate. Later all in metal box, due to the occasional plasma jobs.
Attachment 13082
The program i use is Sketchup, cause i am very fast at it. trying to learn also a proper Cad also at the same time. /NX9/.
Can't wait to see this come together, keep up the good work. :)
I see no point in having 2 ballscrews to drive the Z axis.? Whats the thinking behind this.
Your just making the motors work harder and increasing costs for no practicle gain.? You'd be much better spending the money on a second ballnut and creating Zero backlash.!!
Hi Dean,Quote:
Originally Posted by JAZZCNC
Yeah, what i was thinking, you got me there . I started the design half an year ago, and learned a lot during this time.The thing is that i wanted not only to have 2 ball nuts but also 2 extra ball screw supports, " 4 is better than 2 " to resist the vibration. Thats why the double ball screw. Also the double ball screw saves on the total Z length.
Now i am not so sure. Still its not too late. Now i see that i could have made the ball screw machined so that it accepts double support at the ends. I have an extra ball screw at home, longer, i mean. Then the only thing that needs changed will be to buy 2 longer Hiwin rails to compensate. Have to rethink that. There is still time.
Now going this way of thinking i start doubting if i should not make the whole z axis 100mm longer and have travel of 300mm instead of the 200mm as its now. Could just raise the vertical bars on the sides of the base with 100mm without compromising any integrity. They are ~80mm high right now. the thing is would i really need that extra 100mm and for what?
For The Z or any other axis you cannot rely on a ballscrew to take any lateral load (at all) only a pure as possible long axis load is permissible.
You will need a pair of rails to carry the load. One ballscrew is fine sized according to the long axis load carrying capacity you will find on the manufacturers specification. Bear in mind the impact hammer will apply a large dynamic load to the ballscrew, You may need to use a higher rated screw to cope with this. I would contact the screw manufacturer and ask for advice.
When setting the rails and ballscrew up they must be perfectly collinear or you will be applying a forbidden lateral load as the paths interfere with each other.
Regards
John
How does 2 screws same length give extra travel.? Edit: Ok re -read under stand now 2 ballnuts in parallel is less length than 2 nuts in series.! But still bad idea as it will be quite hard to ensure preload is correct to give zero backlash.
Unless your spinning the ballscrew at very very high speed then at this length vibration shouldn't be problem if supported at both end. If your really bothered then use fixed bearings at both ends and tension the screw.
Personally I would just use fixed at both ends with tension and double ballnuts, this will be more than enough.
John I don't think Boyan is trying to use ballnuts to increase strength just lessen backlash and vibration/whip on screws.!
Reflecting on the dynamic load applied to the ballscrew by the Impact tool.
For many reasons I would prefer to use timing belts instead of ball screws. They do not suffer brinell pitting damage
This search came up with some useful links.
https://www.google.com.au/#q=brinell+pitting
I built this router with timing belts (The Z axis only in this machine is a ball screw but that could be changed)
I know the budget is finite but would it be possible to make a belt driven machine Or two machines One for impact work and one for Routing? Maybe sharing the electronics?
This Is the Router I built with a mate using timing belts for a non profit Men's Shed. http://www.machsupport.com/forum/ind...?topic=23730.0 There is a small video. It works really well and is used by the group so much there is a waiting list.
Regards
John
Thanks John,Quote:
Originally Posted by John McNamara
-Yes, we are talking all the time of long axis load. There will be no side forces or if there will be, they will be smaller than say cutting aluminum.
- the dynamic load of the hammer is not big at all, as the head of the hammer will be small, anyway, the hammer can not produce such a force as one can suppose.
-The collinearity will be way under specifications of ball screw or rails manufactures. I can easily make them collinear to something like 0.00mm
Ok, thanks for the input.Quote:
Originally Posted by JAZZCNC
The design as its now and i have the elements already at home, implements that the both screws have fixed bearing supports at both end.
So you say there will be no sense to make the design as you suggest with one ball screw, 2 nuts and 2 and 2 fixed bearing supports at both ends? I mean only one fixed end will be enough? The bearings doesn't seem very big to me.
Quote:
Originally Posted by John McNamara
I know about the ball deformation. It doesn't bother me though. The hammer head will be half 10mm diameter circle . The air in the hammer dampens the hit, the material is very stretchy too/1-1.2 mm normalized sheet/ , the whole sheet stretches also, not only at the point of hit. More or less the hit will equal to 1 bearing ball hitting the material. This would be spread to all the bearing balls in 2 ball screw nuts. I am not sure how many are they. means that its not like a hit on hard rigid surface
I was contemplating this belt driven. What i want right now is the following. To finish the machine as faster as possible. To try the hammer thing at least once. to draw conclusions and not break the precision of the machine in that process. To use the machine right away to make a new one, simpler, with homemade ridgid elements, belt driven as you say and most importantly 5-6 axis. I almost have all elements for a new machine, apart of this one.
You miss under stand me I think.? . . . . . I would use 1 x screw with 2 fixed ends and tension the screw and if backlash was important then I'd use 2 ballnuts.Quote:
Originally Posted by silyavski
Correctly sized screw will have no issues with this setup if the forces are small like you predict.
Dean thanks for your time!Quote:
Originally Posted by JAZZCNC
I started already redesigning it to go with one screw and 1 or 2 nuts as you suggested. That will save me for a beer or two. I understood you correctly, but messed with my English.
What i meant is if there would be additional benefit if i fix that screw both ends with double fixed end supports, meaning 2 supports each side chained together and then tightened by the nut at the end.
I have seen Pre tensioned ball screws in large CNC machines, Also many where one end is fixed in preloaded angular contact bearings While the other is allowed to float in to allow for changes in temperature. The floating setup may be a less difficult setup to use, particularly if the frame is lightweight. If you pre tension you are imposing a substantial load on the frame, It would have to be stiff or it may be deflected out of alignment by the preloading stress, and the deflection would be likely to vary with temperature.
Silyafski, I really don't know the first thing about making those drum surfaces but the other day I saw this video and thought if this kind of forming process might not work for you as an alternative to hammer forming the sheet metal.
https://www.youtube.com/watch?v=eh0d...8P7aRhF_WqV0Ug
Exactly. Thats one of the reasons i made such strong Z and the cheese holes on the Z. I will not push the spindle bearings, instead will fit it somehow directly to the boxed Z.;Quote:
Originally Posted by mitchejc
Some updates. 2 very hot weeks, especially if you are working alone in 70% humidity, 40C temperature and soldering all day long +weekends and moving heavy stuff.
Had to clean all stuff from the garage. Draw white lines for the footprint. This machine will take a lot of space. Of course it rained right after i took everything out, did i tell you it hadn't rained like 11 months.
Attachment 13315
Started with the gantry. decided to keep sides square, so later could flip and support easier the gantry. Do you see the blotch further on the floor. Guess what, just before starting all my boxes with paint fell on the floor and some spilled. A little diversion :-)
Attachment 13316
I have mixed feelings about the Evolution saw. While the motor and blade is great/made in japan/ the saw is very very flimsy. Next project will be to throw away the base and do a new one. I wish i have bought the Makita. It was 100eur more expensive and don't come with blade- another 100, so thats why. Anyway, an essential machine for the project.
Attachment 13317
Ventilator to cool myself and change of plans. The 60x60 profiles cut to size that were meant to support the rails were discarded. There was no way i can solder them from all sides. Instead i cut all of the 60x10 plate/6m in total/ and decided to separate them by the 60mm using at least the profiles i have already cut. Some carefull soldering from here and there. Very rigid result.
Attachment 13318 Attachment 13319 Attachment 13320 Attachment 13321 Attachment 13322
As you see from the pictures above everything is soldered till the end. Now there was another momentary decision. No legs for now untill i decide something clever and the steel from the legs went just inside the sides of the machine. So stair like sides with no holes, there lie the rests of the profiles meant for legs.
Attachment 13323
I cant explain how strong that machine frame feels. Including that bestial gantry. Vertical bend or twist- i did not even bother to measure it with the indicator. Its solid as a rock. starts to look like a Frankenstein thing from movie.
So today i finished working at 20.30 and couldn't help but move all elements with last available effort, as i wanted to see how it would look. I am a strong man, no lift or whatever help, so i am becoming stronger moving all day these pieces around while soldering. Did i tell you that all the soldered pieces weight around 500kg .
So here is my baby. Its huge. I am a bit surprised how big that is. Still has no name but i think it would be something military:
Attachment 13324 Attachment 13325 Attachment 13326
So after ~15kg of wire, 2 CO2 bottles and some crazy days i start to see how will look. Still have no color in mind.
looking like a really solid lump!!! How about drab (a sort of olive green) and "big bertha"? Well done. G.
I remember it was Mid Brunswick Green that was the preferred colour year ago.Quote:
Originally Posted by GEOFFREY
I have found you a ball screw to fit it:-Quote:
So here is my baby. Its huge. I am a bit surprised how big that is.
Attachment 13332
You might need bigger servo's though. ..Clive
:hysterical: where did you find that ball screw picture?
Olive green is a good idea. Some pieces black or and dark grey. I tried with the other green Mid Brunswick Green, but did not like it
Unfortunately someone took the name big berta . But lets make it alive, then the name.
Today started soldering the bed frame and bought the epoxy. As i stopped working at all except on the machine, money flows like water through my fingers. So i bought at the end the Spanish epoxy with very similar properties like the WS. from choice of three i choose the most similar. There were seemingly better though some data was not clear, from the one that could concern, i mean. 125eur with shipping for 5kg pack +1.6kg hardener.
Basically 90 min gel time, max isotherm 40C, compression strength 580kg/cm2, yellowish, contraction 0.1%, density 1.08 gr/cm3 which roughly translates to 6.5l so ~20eur /lit mix, I cross my fingers that it works ok.
Attachment 13341
It seems that the machine will lay on the floor with no legs. have to figure where to fix some hooks for the future and most importantly some plates to lift it using car jack. To level it for the epoxy pouring. Cause now it is unliftable already.
I made it on my router with the 4th axis.:highly_amused: ..CliveQuote:
:hysterical: where did you find that ball screw picture?
el martillo de Thoryavski
Now going cheap was really bad idea. Ok, it would have saved me 100euro on this size of structure...Quote:
Originally Posted by silyavski
But here is what happened:
The epoxy poured extremely well. It leveled well. And for 4 hours it was perfect. As gel time was 90min, i thought well, i cheated destiny. But no. After the 4rth hour it shrank in volume and there was not 20mm wide flat area in the center to munt the rail. I did the test 50mm wide channel, instead of the 40mm normal with WS 105+209. Read a lot why and it seems the reason is that the epoxy is low quality and contains non reacting solvents that vaporize when the hardening starts. On the long axis it was straight, so its not a mixing problem, anyways i mix it at least 5 minutes and change the can before pouring, so not my mistake. Repeated twice the test-same result.
So i took a risque and lost. My reasons were not that i am greedy, but the price difference multiplied by the future machines is quite some money. However i just returned the 5_1.6kg epoxy so the loss is about the cost of shipping, the time and 1 lit of epoxy.
Conclusions:
1.Seems the biggest unaccounted problem for that purpose is the shrinkage, in other words the purity of the epoxy. Hence the price of good epoxies :-). Otherwise flatness and surface quality is more a result of good mixing and following exact mixture to the gram and temperature when pouring.
2. Judging epoxies from their technical sheets means nothing. It can seem on paper right but poor in reality
3. Epoxies with very high viscosity >700 cps of mixture maybe contain something that will evaporate later
Left on the picture is WS 105+209 at the time of pouring and cured. Also the spanish epoxy untill 4h. Right is the shrinkage when 8h passed
Attachment 13381
At the moment of pouring till 4h
Attachment 13382
The problem after 8h of curing, a bit difficult to be seen but the drawing above shows it better. On the second picture the shrinkage lines can be seen at the reflection distortion . Not that it could not have worked as we are talking about 0.3mm here and on the long axis was straight, but not worth the additional fiddling.
Attachment 13383 Attachment 13384
I don't think that you can blame the quality of the epoxy. It did what it was designed to do. I think that epoxies containing solvents are typically used for coating, so that they spread well - which is what your epoxy did! They are definitely not recommended for use as adhesives or fillers, mainly because of the shrinkage as the solvent evaporates. However, I didn't know this either until a couple of days ago when I read an article on the use of epoxies for adhesives and coating! Something to watch out for if anyone is looking for an alternative to the usual named brands.
Hi Neale,Quote:
Originally Posted by Neale
This is specifically a casting epoxy, its not a coating epoxy. It specifically says 0.1% shrinkage in its technical sheet, and by no means its a cheap epoxy , its simply cheaper than imported WS epoxies.
I also read a lot of documents about epoxy and all say the same- 3 types of shrinkage, and exactly this type is due to non reacting solvents. This is not shrinkage due to temperature cause it happens after the initial hardening. From the company started to argue with me, saying this is not possible, it never happened, until the moment they understood that i know a lot of sh^t about epoxy and they agreed that this was because of the cheap solvents. That was the moment they agreed to break their policy of no return, once its opened.
What about adding a filler like ATH ?