This is a smart modification to make on our 1500mm Axis. Continual improvements on our machines by the Worldwide Open-Source Community is exactly what we like to see by our customers. We love to see this type of feedback and will keep this in mind for our future designs. Great video, GREAT BUILD!
I'm planning on ordering one from you in the next month or so. Would you be willing to either have an extra 1-2 inch length added to the lead screw or have the extrusion cut down by that much? Thanks!
@@sethl1515 Hi Seth, if you contact us prior to making your purchase with this request we can change the Lead Screw Length for your order so that you can implement the feature in this video. Please contact the customer support of the sales channel you choose.
The change of the bearing to the outside of the endplates is a good idea but with the tension applied to the roller bearing in the "wrong" direction will cause the roller bearing to fail quickly, it may be a advantage to place thrust bearing between the roller bearing and the collar. To minimise the dust to settle in the open thrust bearing i made large washers with dense felt that fit snugly over the thrust bearings
This a great stop gap solution. The true problem is the lead screw diameter is under sized. Shaft whip is to be considered on any rotating machinery and is dependent on the length to diameter ratio of the shaft, shaft tension and rotation speed. Shaft whip is mostly due to to the sag of the shaft over it's length, which is an eccentricity, and when rotated, causes the shaft to whip. Tensioning helps by reducing the sag, but will not remove the whip fully. It just changes the critical speed at which it occurs. Such a long length of screw would need quite a large diameter screw to eliminate whip completely.
Yes, I was thinking the same. When he said 8mm screw I thought that is a mistake - it should be 12 mm at least or maybe even 16 mm to stop it from sagging under its own weight. Sean found a solution that deals with a part of the problem, eliminating some of the additional forces, applied externally, by the frame. However there is a caveat to increasing the diameter, because the added weight of a 12 or 16 mm lead screw will introduce some other factors into the equation, putting more load on the motors. I am not familiar with this machine, but if the motor on that axis does not have enough torque, or it's already at its limit... well, it's game over. Maybe the fact that they kept using a 8mm lead screw in such a long axis is in fact a compromise - power vs weight... Also, another thought is that reversing the support plate and putting tension on that lead screw will modify the geometry of the whole frame a little bit. It would be nice to see a test with a simple square carved in a piece of wood and measure the deviation that occurs...
good job m8. but they are roller bearrings you need thrust bearrings for that application. i have a 1515 and no whip but bulkman can shove their instructions where sun dont shine. in the end i built kit my way and it works. roller bearrings dont work under side to side compression. thrust bearrings are the only logical way to put rod in tension .
Thanks for the video. Was having problems with leadscrew whip on a Workbee 1515 and this is a fantastic solution. Purchased longer leadscrews from Bulkman3D to avoid trimming the v-slot and cbeam. Looks like Bulkman3D is now selling the 1500mm kits with longer leadscrews and a tool to help set the tension.
I have one of the very early 1000mm x 1000mm Workbees and, being a cheapskate, I don't want to scrap the existing lead screws for ones only a few millimetres longer to allow tensioning the lead screws with a clamp on the "free" end. I plan to drill and tap this end of each lead screw and locktite a 14.9 grade M3 stud in. This will allow me to tension the lead screw fairly accurately because the tension can be obtained by stretching the lead screw by a well controlled amount using the fine pitch of the stud. For a 1000mm lead screw I estimate we need of the order 0.2mm of stretch to obtain around 100kgf tension in the lead screw.
So is the 1510 or 1515 lead screw workbee is now consider as stable and reliable as the 1010 ? (Not as "accurate" and rigide of course) Also do those nut wears on such high speed ?
@@geekoid183 By tensioning the screw the whip can brought down to the same level as a 1000mm screw un-tensioned. But it is considered as stable with the screw tensioned.
Bulman3D included a black threaded plastic knurled knob about the size of a hockey puck, labeled "Lead Screw Tensioner", with my recent WorkBee kit. You can use it to load tension on the lead screw and then tighten the lock ring. Works great...
Wow. I actually ordered and installed a new 1500mm ball screw, knowing that the original had a slight bow to it when it was installed. Bad wobble if I pushed it much beyond 250IPM. I was able to achieve well over 100IPM faster with the new screw, but only for a couple of days, then the wobble returned, mysteriously. In the process of troubleshooting the issue, I stumbled upon this video. Since I designed and built my machine, it was easier for me to introduce tension on the axis. What happened? when I loosened the BK12 mounting bolts and pulled on it to add tension, it came right off! The Jesus clip that was supposed to be holding that end of the screw fixed had fallen off, which likely led to the wobble in the first place. I replaced the clip, tightened her up and kaboom! No more wobble! Now I need to get better Jesus clips... Sincere thanks and best wishes!
Hi all! Instead of using a collar with a machined grub screw, why not use a brass lead screw Nut to adjust the tension on the main lead screw the support bearing has to be the type that accepts radial load , suggest drilling and taping the brass lead screw nut to keep it from turning to keep the tension on the main lead screw!
I used the thinnest oil I could find. SAE 10 I believe. Sawing machine oil. It's been OK for quite a while. I keep an eye on it for dust and the like, but so far, problem fixed.
Thanks. The clamp was a great idea. I just moved the gantry to the center of Y and then pulled the lead screw by hand to get a slight tension. You are right, btw: Workbee does supply longer lead screws in their V2, with 'Tingle Tension Extensions' is what they call them. I might order longer lead screws and put some push bearings on the outside. Regular bearings are not supposed to handle axial forces.
Just a thought. Might it not be an easier job to get some of the brass lead screw nuts that is available and use that as a tentioner. You will still need to drill and tap for a grub screw to lock it in place. just google 8mm lead screw nut if you want to see what it looks like.
thats still quite allot of whip, what i dont get is who thought compression was a good idea ? when tension used be aware you need to change out your bearings , to trust bearings not only axial. or you will destroy them in no time. nice video anyhow !!
I think if you are in compression, 1.5m is pretty unusable. If you are putting the srews in tension, you are probably OK at the longer lengths. You will likely find it necessary to apply a greater tension preload and will need thrust bearings.
That was not the purpose. The purpose was improving performance during rapids. It allows the machine to run at a faster rate without problems. There have also been instances where people have bent their lead screw. This will prevent that as well.
Thank you for the video. I currently run a machine using belts and was looking for an upgrade with screws and a bit bigger. I was looking at the Workbee at the same size you have. Being able to use screws on that size helps my decision. I realize you may not have any context on this but I'll ask anyway. Do you think there will be much difference in accuracy between the 750x1000mm one and the 1000x15000m one? Due to greater flex in the Y and X spans? I would love to be able to mill that size but not at the loss of accuracy. Any shared experience would help greatly. Thanks.
Hi Sean, cam across your video. I am considering a CNC machine to get into making some wood and metal projects, carvings, cut outs, etc. I don't know much about them but I have a limited budget. What do you think about the Workbee CNC's? Looks like the kits come with everything but the MDF table/platform.. Do they have the ability to set the zero level against the surface you are working on? Would you recommend air or water cooled? Thanks
If you are looking for a hobby level CNC, then you will do well with the workbee. I think for a first timer, you want to be sure you understand the entire drawing, CAM and control dynamic. Be sure you are purchasing something that is not a significant stretch for you to learn. Mach3 as a control software is very tricky to make work for a new user.
With the locking collar on the opposit side of the end plate, you need that distance. It's possible you could use the shaft coupler in place of the locking colar though. I'm not near my machine to measure those parts. It moght work.
I've contacted a seller and they've offered to give me an extra 10 mm added to the lead screw length. Do you think that will be enough to get the bearing and collar on the outside?Thanks for the video. It alleviates my worry about getting the bigger machine
I was hoping for something longer as well, but I think the lead screw situation makes it near impossible. There is too much bend or deflection. If there was a rack and pinion version, that would make it possible.
You could check motor tuning in ports and pins on MAch3 or confirm that all axes are set up the same. Or one could be micro stepping and the other not. That's typically specific to the driver or the dip switches or jumpers.
The challenge with that approach is that the motors have to lift the weight of whatever axis is being moved against gravity. You would need bigger stepper motors and possibly drivers too. There may be additional wear on some components too.
I just ordered the 1500x1500 from bulkman, I'm wondering wouldn't a multi start screw lessen the whip? I'm thinking a 4 start 3/8" acme rod. What do you think?
The Whip has to do with the fact that the screw is under a buckling load that actually buckles it. A 3/8in screw is going to buckle under a similar load to a 8mm screw. The only way to combat the problem be changing screws is to go with a larger diameter screw.
@@grahamshere I'm not sure how a bigger motor mount would help. I'd need to see your solution. As mentioned, cutting the c-beam is not necessary if you get longer screws. I was unwilling to wait for them and did not feel that shortening my c-beam by 1/2in impacted my travel enough to be a problem for me. I can still cut 48in of material, so a partial 4'X8' sheet is no problem.
In tha t last section I was running at 5000mm/min which comes to 196in/min but in testing I believe I was at 8000mm/min which comes to 196in/min. I think the problem I ran into was motor stalling at that point. I'll likely go to a 36V power supply and bigger motors.
@@TheFeFactor I forgot to say that in the video so I put a note at the bottom of the screen. The end plates on the opposite end of the machine are also swapped. This is very important to being able to tension the screws.
@@seanmartin8770 for a while now I was thinking to tension the rods and while preparing for it I got a set of this clamps www.amazon.com/gp/product/B000IL5GPK/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 they should have a very good holding power.
I have 4 CNC routers in Watkins Colorado and one in Berthoud Colorado. Interest would depend on timing. Right now the 3 commercial machines are running our jobs 4 days a week 10hrs a day, but it's a seasonal thing. You can give me a call if you like.
would adding springs between the end grub and frame give you even more tension? www.mcmaster.com/9657k636 one of these springs on each end would give you an extra 20 lbs of tension. why didn't you just increase the threaded rod to 12mm?
Who the hell would use 8t trapezoid 2mm pitch power screws in a cnc table lol? Wow you got screwed literally if you paid for those. Those are designed to be used with 0 to 80rpm inmind to start with at a max length of 400mm. That is spec rated for those screws. Provided you have 304 stainless screws and 8070 copper nuts. Anything above 80rpm will damaged those with a force greater then your wife bitch slapping you for wasting money on that. 1200mm 12mm ball screw with bearings and nut. 0 to 850rpm cost 55$ and won't bend anyhow cause of its twisted design even under loads. Not as much friction and does not turn to a sloppy mess. Acme screws are not even designed period to be used with any kind of stepper or motor. NOT trying to be the black cloud here but worked the BRAND name Canada product would never used acme screws in a product. You got what you paid for a China knockoff