Avid Leg Kit to weak?

Hello All.

I’m getting ready to purchase a new machine. The Avid pro 48x48 is one of the machines on my short list. My question is that it seems these machines really move around while running. I just watched Mark Lindsay run his new machine as was surprised how much it shakes while running. Is it just because of this light weight leg kit? I have a welder and can fab a much stronger legs and make a table for it to sit on. Would that take care of the shaking then? Just don’t want to drop 12k on a machine that jumps around the floor. I was also looking at the camaster stingerll which has a steel frame. Thanks

I have the 5 x 10 machine and the extra bracing. We use the space underneath for timber storage and with this below, the machine doesn’t move.

If you can get a frame fabbed I can’t see a reason not to! The website has great detailed plans to work from

I’ve seen that video you’re talking about. That amount of shake is not typical. Looks like there might be a setup issue there, or something going on with the floor.

The 8020 frames are surprisingly stiff given their size. Before I worked at Avid CNC I had a bolted steel frame machine in my production shop that was much heavier. Having now run an Avid on a lot of the same work I used to do I can say that this machine is better.

We do have customers that make their own bases or add extra bracing if they feel they’d like to, so that’s always an option if you have a specific need.

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The machine is all aluminum and can shake a bit under high speed and sharp direction changes. Camaster are good machines but have heard they are unfortunately having production issues. Also to get a Stinger of similar size I would think you would be spending around 20k if memory serves. I don’t run my machine at the limits like some do so I see very little shake or vibration. These things can also be tuned in the motor setting for longer decel and accel numbers.

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As others have stated I believe the major issue is the lack of enough counter weight in the base, not the flex in the leg kit. I would focus on how to add weight instead of re-enforcing the frame, then re-access the performance. The CAMaster is a great machine and you avoid having to assemble it yourself but you do have other issues and expenses getting such a heavy machine into your shop. I seriously considered the CAMaster before I purchased the PRO 4848 and have never regretted the decision to go with the Avid.

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I have the 4896, no shaking at all, so if built to spec, you shouldn’t have any concerns

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I have a pro 4848 and yes, there is some flex in the frame depending on how you are cutting.
I keep my rapid at 50 to 75 percent and dial down the feedrates depending on the job.
I have a bunch of live edge slabs, abot 55 inches long under the table and that does a good job of dampening. A nice heavy custom made table would not hurt it. I was going to make one myself, but just did not have time, so I got the leg kit.
I am very happy with the Avid, and also thought of Cammaster. They do not communicats very well imho, while Avid could not have been more helpful.

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I ended up making my own stand. I used pallet racking and welded extensions in the match the width of the machine.
I also turn down the acceleration on the steppers from 50 to about 25. That way when your machine accelerates it’s not trying to get up to max speed instantly. This really cut down on the shaking when rapid direction changes are taking place.

I saw that same video shortly after ordering my PRO4896. I was quite concerned. However, now that my machine is assembled I have zero worry. My machine is solid as a rock. I did add a few more extrusions for a storage shelf, but even before that I couldn’t get the frame to flex at all.

If you dig into that guy a bit more you will find he was being paid by an AVID competitor.

Thank you all for the quick reply. Sounds like if i do go with the Avid I will make my own legs. To get a larger machine bigger than the 2x4 that everyone seems to make the choices are kind of limited in that price range of 10K or so. Seems the only ones I have found were the Avid, Phantom and Axiom.
Mr Nick did you make a flat top for the machine to sit on like a large table?

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Something to remember about my setup is that I’m in basically a 12’ x 16’ garden shed. The floor is 3/4 inch pressure treated plywood, with 2x6 floor joists spaced 16" on center. I’m not on a concrete slab. As for the stability of the leg kit, there is no issue there. It’s solid as a rock.

The shaking issue may have been caused by my concern about overtightening fasteners when I assembled it. I watched another guy assemble his Avid on YouTube, and he sheared off several bolts when he put his together. So, I guess I was a bit paranoid when I assembled mine. I’ve emailed back and forth with Eric, and according to him, if you grab any of the front or side rails and shake, it should not wobble. I tried it with mine, and I had a little bit of wobble from side to side - none from front to rear. It looks like I need to go around and snug up some bolts.

As a side note, I’m former army aviation, and I got used to using torque specs on fasteners. I researched torque values for using steel fasteners in aluminum plate or extrusion, and that has worked just fine. I couldn’t find anything for a steel fastener in a t-nut. If anyone has any references, I’d love to check them out.

Like many, I’ve watched just about all the YouTube videos out there on the Avid CNC and regidity was a concern. So, when I ordered my Pro 4896 CNC, I also ordered extra extrusion of both the electronics bar (4x1080mm) and the frame cross member (1x1250mm). I believe it cost another $300 or so. I also opted to go with a one piece frame extrusion (2850mm) instead of the the Avid two piece (1600mm+1250mm). I’ll use the extra unused extrusion for other projects in the shop. The only issue was, I had to physically pick it up from 80/20 Inc. in Indiana (ups only ships up to 108 inches, not 112.2 inches) and trucking it would’ve been a more costly option. I believe it was about $400 + travel, an extra 11 hour round trip drive, but we’ll worth it. With the added electronics bar extrusions, I boxed in the bottom of the legs making sure the tops were coplanar with the leg assemblies. I found some very reasonably priced 5’x8’x1” MDF to put on top of for extra weight and storage. I’ll then use the extra frame crossmember for a vertical table. That along with reducing the acceleration makes for a rigid base, there is some movement in the gantry, but it’s minimal. Deviating from the Avid assembly instructions does require some fore thought, but all went well without any snags.
You could also order directly from 80/20 Inc. for any additional extrusion needs.

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I have a pro 4896 with NEMA 34s and the key kit.

If you don’t need to disassemble the table to get it into your basement, or are running in a garage, etc. it makes more sense to go with a welded steel table. It’s probably cheaper too. It is certainly far more rigid.

I’ve had to turn down my acceleration, adjust feeds and speeds, etc to ensure precision. For example
I had to bore about 200 3/4 in holes in 3/4 plywood. The space under my table is full to the top with rough hardwood lumber 8- 10’ long, 1-4 inches thick. It’s hundreds and hundreds of pounds of added weight.

With the default settings in Mach I was still getting oval holes. Slowing everything down fixed it. Rigidity is certainly a factor. It’s not an issue for me anymore, and it is an acceptable trade off to be able to run a 4x8 cnc router in the basement of my 1800’s house. If I had a garage I would go with a welded table.

I have a 4x8 Pro Nema 34 table with the leg kit on a concrete slab.
I’m definitely gonna do a welded steel table here soon.
The aluminum leg kit is not acceptable to me. Far too much wobbling and shaking.

I opted to build my own base using 4x4 braced pressure treated and put in on locking poly casters at each corner for occasional mobility. Then I added 6 industrial grade machine base feet on a length of all-thread with heavy washers and locking nuts. When in position I drop the feet, use the adjusting jam nuts to get it firmly set, then level, and lock it down, usually the poly wheels are then slightly off the floor but the machine is firm and solid and I’ve had no vibration or movement issues. When I need to move it, raise the feet, unlock the poly casters and it rolls easily. I built the 4x8 machine with extended gantry, no issues with it vibrations or moving around at all.

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Call me a stick in the mud but welded steel isn’t the answer either. All of my rigid steel cutting machines have cast iron bases. In fact, the only steel on these things is the coverings for all the electronics and stuff.

What you want is an ASTM A48 Class 40 (Dura-Bar anyone?) cast iron base. It is cheap. It is easily machinable. It has dampening characteristics which reduces ringing (thank you large graphite crystals). It is also very stiff and resistant to flexing.

You can get it cast using green sand and closed cell foam masters. Then get the critical parts machined on it like the rail and rack mounting points.

I have to admit I am a bit perplexed why small CNC manufacturers don’t use more cast iron. I think they don’t realize just how cheap and easy it really is.

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Thanks for the advise. I have talked with Avid a while back about making a 3x3 bench top unit. Can they make it any bigger than that?

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Hey sorry. Just seen your reply.
No, the stand I made has all the weight of the machine resting on the side rails. I’ll attach a image showing.
When making it I used the pdf from avids site with the dimensions of the machine. Subtracted about an 1/4 for clearance on each side to give the steppers room to travel. In the end it worked out very well but I won’t lie. I made the stand while I was waiting for the machine to arrive so I was nervous about my tolerance choices but it worked out really well.

im actually thinking of attaching long sheet metal panels on mine…then bolting those into the extrusion

Hi Mark,
I have been using my 4896 Pro for the last 6-7 years and i never experienced any shaking or movement on my table leg kit. I’m on a concrete floor and I do use the table kit as a wood storage area and it does make a difference I bet.
Could also be some acceleration parameters in Mach3/4
Great cnc…

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