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Here's what I made, here's a photo, and here's a link to the [[page]] on RepRaps wiki!
Re: Polar Rep Rap - 14 years ago
Yes two SCARA robots in that configuration would reduce the cantilever loading, but the downside would be the working envelope would be reduced to between the robots as it could not rotate around the primary axis too much. I'm just thinking whether ther robots would be better at 90 degrees or 180 degrees from each other. A SCARA robot really appeals as the area above the build platform is relatiby martinprice2004 - Polar Machines, SCARA, Robot Arms
Re: Polar Rep Rap - 14 years ago
I was doing some calculations and a few sketches on CAD for a SCARA robot design similar to the configuration below. Working on a 200mm square build envelope I calculated that to get an XY resolution of around 0.1mm using stepper motors the motors would need to be geared, but this could be achieved with toothed belts and a single intermediate gear. Something like 100:1 for the overall reductioby martinprice2004 - Polar Machines, SCARA, Robot Arms
Re: Design for low cost delta with 3 servos - 14 years ago
The delta robot looks a really nice design and would be very useful for pick and place work. I think a delta design like you have may not have the accuracy of movement you require for fuse deposition and if it does will not be able to achieve the speed of head movement you are looking for. I did consider a servo driven delta for my Helium Frog design, but after reading up on them decided to goby martinprice2004 - Delta Machines
Re: Polar topologies - 14 years ago
Sounds like quite a neat idea rotating the platform by 1 rev to act as the z axis, but a thread with a pitch of say 0.5mm would probably be very small in diameter. For example a standard Metric M3 has a pitch of 0.5. You can of course manufacture a thread with any pitch you want, but this just adds complexity. A simpler method than an angled bed would be to have the bed rotating around the centrby martinprice2004 - Polar Machines, SCARA, Robot Arms
Re: Anti-ooze nozzle - 14 years ago
QuoteUnless the object is a perfect rectangle you will do considerably more head movement than is currently done and the quality would suffer significantly. If you could explain the perfect rectangle theory I would be obliged as I am a little confused. Consider how in the early days of printing, most large drawings used a pen plotter to produce a drawing much the same way as Reprap machines woby martinprice2004 - Mechanics
Re: Anti-ooze nozzle - 14 years ago
Reversing the motor does overcome stringing to some extent, but closing off the flow would be much better. There are quite a few advantages if you could close off the flow accurately as follows:- 1) It would mean that you could produce a part scanning the head back and forth like an inkjet printer rather than a complex path like we have to use at the moment. This would be much faster than what wby martinprice2004 - Mechanics
Re: Anti-ooze nozzle - 14 years ago
My idea was not to use a fuel injector, but to make a valve like the end of the fuel injector and use a standard reprap nozzle and wire feed. These type of conical valve seats can stand incredible pressures (1800 bar) without leakage so would be ideal for this purpose. They seal much better than a side actuating valve that Adrian was using in his setup. I would use a standard nozzle and machine aby martinprice2004 - Mechanics
Re: Anti-ooze nozzle - 14 years ago
First my apologies for adding to this old post, but I'm an Automotive engineer and the best valves I have seen and neatest operation are fuel injection valves. They use a concentric pin pointing downwards to the end of the nozzle. Fuel injector Ignore all the bleed and spring but look at the tip of the injector. I think if you could push the molten plastic from the side to the nozzle and have tby martinprice2004 - Mechanics
Laser Suppliers - 14 years ago
Can anyone suggest where I can buy a 1 watt pigtailed laser in the UK. I would prefer a "shop online" source. I have been looking for quite a while but I think in the UK they think everyone is a potential terrorist and doesn't want to sell this sort of stuff. European sourcing is also an option. I want to try some laser sintering of nylon and this size of laser seems about the best. I'm lookingby martinprice2004 - Laser Cutter Working Group
Re: Helium Frog Delta Robot - 14 years ago
Yes I have been reading up on bowder extruders and hysteresis seems to be a drawaback, but most seem to be able to compensate in software for that. I think it will be sufficent for what I want on the HF Delta. Perhaps the best solution is a bowden extruder with a solenoid "pin" gate at the nozzle. Solenoids are lighter than a motor so you would still have a fairly light head. I was having a routby martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
Bowder extruder, yes that will probably work on the delta. It would benefit from a lighter tool head a well.by martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
Work continues on the delta robot design, I am currently printing some new corner modules to incorporate an extra linear rail. This should eliminate the twist in the vertical carriages and improve the accuracy of the mechanism. There is another concern with the design, The work space above the centre tool platform may be too small to get an extruder with motor in. It may have to be positioned soby martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
I have completed the assembly of the delta robot and it looks like the twist in the centre platform may be an issue.This is only controlled by the lead screws, if the lead screws were not there, the vertical carriages could rotate around the vertical rail which cause the centre tooling platform to tilt a little. The M8 lead screws are quite long and can flex, so I may have to add a second linearby martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
Mike The bearing arrangement you suggested is an interesting one, but on a reprapped machine probably wouldn't work. Your bearing arrangement means that the linear rails have to be perfectly aligned and spaced or the carriage mechanism will either be tight in places or go loose, it could also twist. If you look at the Mendel Reprap design the bearing arrangement uses one bar as the primary axisby martinprice2004 - Delta Machines
Re: RepRap Delta Übersicht - 14 years ago
Gents Here is the design and .stl models. Helium-Frosch-Deltaroboter .stl models RepRap Wikiby martinprice2004 - Altes Forum
Re: Laminated Laser-cut Cardboard - 14 years ago
Some really nice ideas here. Has there been any work done on "Living Hinges" in the reprap community? I think they could work in a similar way to the robot in your first video. Living Hinge The second video I could see using it for mars landers and such instead of wheels, the only major drawback is the use of vacuum energy as this is the single most inefficient way to power things I can think oby martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
nophead Wrote: ------------------------------------------------------- > Why do the diagonal braces go to the mid points of > the top bars? It will be much stiffer if they go > vertex to vertex because any movement of a vertex > would require one of the diagonals to stretch. The > way you have it only requires the top bar to flex > at its midpoint, which is many orders of magnitby martinprice2004 - Delta Machines
Re: Helium Frog Delta Robot - 14 years ago
I have updated the Helium Frog Wiki Page and created a new development page for the helium frog delta. I'll add more details when I can. Helium Frog Delta Robot Wikiby martinprice2004 - Delta Machines
Helium Frog Delta Robot - 14 years ago
I am continuing the design of the Helium Frog Delta Robot and I have uploaded the latest models on the website. I am still working on the central tool platform. I'm going to put on a 3 bolt flange so the tooling can be swapped easily from the top by unbolting and lifting it off. Initially I think I will design a simple pen holder so the robot will be able to draw diagrams on a flat sheet. Thisby martinprice2004 - Delta Machines
Re: Im making a tripod - 14 years ago
Viktor I have been working tonight on the helium frog website and uploaded most of the main .stl models. There is also a .stl file of the complete assembly which you can have a look at. It should give you enough information to work out most of the dimensions and bearing sizes etc. Let me know if there is anything the team urgently needs and I will get on to it tomorrow night. I have models of thby martinprice2004 - Delta Machines
Re: Im making a tripod - 14 years ago
Thanks Viktor I think your equations are more arduino friendly than mine! I shall work on the Helium Frog website over the next few days to try to make it a little more useful for people who are interested in the design and post all that I achieved so far. The designs are in Catia V5 format so If anyone uses this I can include the assembly file as well which may be of use for lengths of the rby martinprice2004 - Delta Machines
Re: Im making a tripod - 14 years ago
I did not abandon the project, but have a few other projects on the go at the moment (Baja Buggy and some animation software). I have completed the frame and now need to finish the central carriage. I notice that the German forum has made some parts similar to mine which is good news and at least shows that I was heading in the right direction with my design. I hope they get further than I haveby martinprice2004 - Delta Machines
Re: DIY printhead - 14 years ago
Some thoughts on producing a plate with a small hole. There are many ways to produce a small hole in a plate other than drilling which is very tricky. 1) A hypodermic needle mounted in a larger hole with epoxy or solder. When dry flash the excess needle top and bottom off flat to the plate with a dremel. You could reuse the flashed off pieces of needle to make more nozzles. (If i remember rigby martinprice2004 - Powder Printing and Selective Laser Sintering
Re: Nichrome Wire Questions - 14 years ago
I always insulate my nichrome wire between kapton tape (usually two layers) before winding it around the extruder barrel. That way you can be confident that you wont get any shorts. I then tape over the assembly again with kapton. Nichrome with silk or enamel insulation I have found to be no use at all, so stick with wrapping kapton tape around it anyway. Its a little more fiddly to get it aroundby martinprice2004 - General
Re: Delta robots - 14 years ago
In theory the gear ratio is just the ratio of the number of teeth ie 128/16 = 8:1. This is provided you have used gears from the same supplier and are of the same module. I had a look across the net and this seems to be the way to do it. If something funny is happening and the gear ratio seems off, probably the best way would be to mark the motor and rotate it a set number of times by hand and cby martinprice2004 - Delta Machines
Re: reprap + metal lathe combo - 14 years ago
spacexula Wrote: ------------------------------------------------------- > The "cooperatives" are already running. > Ultimachine, Makergear, Makerbot, and and some of > the saints on the forum are definitely not getting > rich. I wouldn't underestimate the profits that some of these companies are making. Makerbots are $750 each. If Makerbot sells around 111 units per month I calculaby martinprice2004 - General
Re: reprap + metal lathe combo - 14 years ago
It won't be cost effective to produce your own hardware as stated above, but also the bolt or nut you make probably won't be as strong. For small nuts and bolts, the threads are usually rolled which improves strength and the bolt head is sometimes made by forging / die forming which increases the strength. Washers are generally stamped out from a strip or sheet using a press. As a general rule yoby martinprice2004 - General
Re: Tear Drop Holes. - 14 years ago
For small holes (about 7mm or below in diameter) you dont actually need them as ABS is capable of bridging the top of the hole. My machine is capable of bridging 7mm easily without any sagging. You can set the bridging speed higher in skeinforge so that you get a decent shaped hole. You occasionally get a filament drop in the hole but its easily cleaned with a drill. You can also truncate the tby martinprice2004 - General
Re: Im making a tripod - 14 years ago
I Completed the excel spreadsheet. It may be of use to you when calculating the movement of the vertical axes. See link on left menu of page. Excel Delta Robot Calculatorby martinprice2004 - Delta Machines
Re: Im making a tripod - 14 years ago
I will upload everything If I get it working (under the GNU GPL licence). Even if I dont, I will probably upload the models anyhow as it might be a good start for someone else. The ball joints (rose joints) are slightly restricted in movement, but I believe I have overcome this limitation in two ways. 1) position the joints in an orientation to use the ball rotation on the axis with the most moby martinprice2004 - Delta Machines