Michael.M published a new build:

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Does anyone know the proper amount of tension I should put on the wheels? The eccentric nuts have 6 flat sides and I basically turned each nut 1/6th of a rotation. This made the machine feel fairly solid like the axis wouldn't move if i stood them up vertically. Thanks!

Michael

 

Thanks Rick! I'm completely new to this type of linear guide. Im trying to make this machine as tight as possible. Hey I have another question: The leadscrews I bought have an OD of 7.75mm and my flange bearings are exactly 8mm ID. There's definitely a wobble there. Is this normal?

 

Hey Rick what is the proper way to adjust the eccentrics? Is removal of the carriages the only way? I worry that as I create a tighter fit, the wheels will get damaged when entering the cut end of the extrusions.

 

Thank you Anthony! I really appreciate the comment.

 

Hi Stargeezer,
I began my CNC journey with designing my own machine around linear profiles and ballscrews. I soon found out that either I would need someone to cut some plates for me or figure out a way to cut them myself. I pretty much needed a CNC to build a CNC. So I started looking for affordable options that could mill aluminum, slowly.. I saw the plate maker cutting aluminum and then saw the Sphinx thinking this will be, in a way, a larger plate maker. I liked the way the cbeam created a supported linear actuator. I don't have any experience with poly wheels and eccentrics but I think I have the"feel" for adjusting them after dissasembing my machine a handful of times. I'm actually still not 100% satisfied with my adjustments but we'll see. I feel that in order to take full advantage of the cbeam profile, you need wheels riding the inside and outside surface of the cbeam. I found you also had to take into account the the resistance caused by the double antibacklash nuts on top of the resistance from the wheels. I want a solid machine but I don't want to over stress my stepper motors. Do you know if superlube with PTFE oils / grease is ok to use with delrin? Anyway, before I went this route, I was purchasing parts for my self-designed CNC so I have some nice THK linear guides. I may just try to fit them to the Sphinx seeing how I built this machine with the same dimensions. Thanks for the comment.

Michael

 

Would you mind sharing your source for the .5" ball screws? I'm very interested in using something like this.

 

Is this documented in the morning one of your build? I've been pondering future ballscrew upgrades. I think if I go that route, I will ditch the wheels and use my linear rails. I would basically just be using the cbeam for a ballscrew enclose at that point. This is all just an idea anyway. How well do you think my machine could mill aluminum as it stands? My plan is to use the machine to upgrade itself. Hopefully...

 

Hi Dankarghh,

I will definitely post anything I figure out. I ran into the same issue with the larger ball nuts. I'm debating going with the 12mm screws. I've also read that there are better leadscrews out there.

 

The one thing I don't like about leadscrews is the resistance they create when compensating backlash. Add that with the resistance from the wheels and I'm wasting a lot of motor torque

 

I'm just saying that leadscrews with AB nuts have more rotational resistance than a ballscrew. I adjusted my extreme wheels until there was no play which also added a little resistance. I haven't run the machine yet so I don't know how the steppers will handle it. Maybe it won't be an issue. I've been using SketchUp to test fit the different ball nuts and the 1605 nut looks too big. I would prefer the 16mm over the 12mm screw honestly. I have some thk linear rails that I would like to use somehow. (15mm and 20mm) I haven't figured out how to use them without a complete redesign. That would be a bummer considering how much money I have invested in the current setup. Do you have any pictures of how you mounted the 1605 nut? This could really help me. Thanks for all your support on this subject.

 

I pushed down on my spindle this morning and it actually moves a little and I'm not sure if it's the end of the leadscrews moving in the flange bearings. I see there's a trick to tensioning them but my screws are too short for that method

 

Anyone know if it would be ok to run my spindle cable in the drag chain next to the stepper and limit cables? All three are shielded with drains running to PSU ground. Thanks.

 

Hey thanks for the reply. I think I'm going to get comfortable with the machine before I dive into the ballscrew upgrade but I will definitely keep that in mind.

I've heard of people having issues with noise originating from the spindle cable but I really want to have everything secured in the drag chain. By the way, that vertical mill you made is awesome! Did you anodize your plates?

 

Im just waiting on my small radiator for the spindle cooling system and tying up some loose ends but I should be up and running soon. I keep telling myself it will be ready this weekend but every time I work on it, I find something else I want to add or improve.

 

Oh it looked like the red colored parts were anodized.