weight limits for a buddy 32

[cowboy1296]

I have a buddy 32 prs standard with a 4 ft power stick. i use a lot of rough cut wood which means i have to use my table surface bit to square up the boards. yesterday i was planing a plank of black walnut that weighs 55 lbs. while it was running along the x axis i notice the buddy momentarily bind up and then continued to plane a couple of times. i noticed that my x setting was off about a quarter of an inch. I speeded up my feed rate of 2fps just a tad and no longer had the problem. do you think the weight is what caused my problem. at this point there are no issues to deal with since i was only planing but when i start to cut this large sign i do not want any issues.

[dana_swift]

Rick the issue with weight is at what point does the friction become enough that the stepper motors lose counts. That is exactly what it sounds to me like you are describing. I am presuming you have a Buddy32 Standard.

Several things you can do is make more shallow cuts, especially at the beginning when the log is the heaviest. Then as the weight drops make heavier cuts. The cutting forces add to the friction from weight.

Slowing the cut helps, and I will let someone with a standard buddy speak more on the speed/weight issues. That makes smaller chips, so I recommend you try the shallower cut depth.

Also use your sharpest newest bits which will have the lowest cutting forces, that might help also.

That is exactly the situation the alpha systems take care of, they detect that the weight has caused a loss of accuracy and add additional steps to correct the error. That is of no concern if you dont have one.

My buddy 32 is an Alpha, and I haven't ever seen missed steps from weight with any of my powersticks. I have had it fault when something is binding, but it detects the error and shuts down the driver.

You might ask SB tech support what they have experienced as a practical weight limit. There is no set number as it depends on so many factors.

If I had a wish list item for future shopbot development, it would be a %power readout on each axis to let me know how much I could increase the depth of cut without stalling the motion system at the weight of part I am cutting.

Our buddies are more sensitive to this than the gantry systems, as the part weight has to be accelerated back and forth all the time.

Hope that helps

D

[cowboy1296]

thanks. yes i do have a 32 prs standard with a 4 ft power stick. i am not in any kind of business and most of my stuff has been donated to a church or veterans groups. the one i am working on now goes to a privately funded organization that supports wounded vets returning from the middle east. where i am going with that, is for the occasional sign i thought that the prs standard would fit my needs. i found the black walnut to be softer then some oak i worked with recently and my cut depth was shallow, maybe a tenth of an inch. the oak caused me no problems but i was working with a lb board also.

if it is the weight that is causing the problem for this project i can cut off a foot of a 4 foot board and maybe i should to reinsure it does not happen during routing.

thanks again

[cowboy1296]

got feed back from tech support, 55 lbs should not be an issue and they suggested checking mechanical settings and grease it. a question on grease dana, do you put so much grease on it that its dripping off or just a thin layer.

[erik_f]

I use lithium grease and put on a thin layer. There may be better types of lube for your rails, rack and pinion, but that is what I use. I wipe down the rails regularly and re-grease. I generally just use paper towel.

[cowboy1296]

I wiped them down, regreased and my 55 lb board worked just fifne. Thanks for the reply

[dana_swift]

Rick- just noticed your post.

I use white lithium grease, and probably dont do it as often as I should. But its just a dab on the rack gears in several places. I run each axis to its limits a few times to spread the grease. There may be a much better way, but thats what I do.

I dont want anything greasy dripping on good hardwoods! I dont grease my rails, probably that is a good idea, but the V rollers should not be sliding over the rails they should be rolling. The bearings in the V rollers may need greasing, but I have not so far. I could add the V rollers to my maintainence if that is a good idea.

D

[ken_rychlik]

They make a can of spray grease for lubing garage door tracks without collecting a bunch of dust and dirt. I get it at the big orange store and I like it much better than the old brush and grease bucket.

[cowboy1296]

i like that idea but what is it called?

[mtylerfl]

i like that idea but what is it called?

Hi Rick,

I use TDL (called...The Dry Lube). The spray can has a big "TDL" on it. Home Depot and Lowes has it here.

[mikem]

Hi,

I saw this post and reference to contacting tech support. Tech support suggested I go to the forum. I have a Buddy32 Standard and just added 8' powerstick. actually 10' (8' -x travel). I have attached the shopbot outfeed rollers. What I'd like to know is approximate weight the Buddy32 will handle for the x axis. Support table, sacrifice table, clamping, work piece.....

Thanks
Mike



Rick the issue with weight is at what point does the friction become enough that the stepper motors lose counts. That is exactly what it sounds to me like you are describing. I am presuming you have a Buddy32 Standard.

Several things you can do is make more shallow cuts, especially at the beginning when the log is the heaviest. Then as the weight drops make heavier cuts. The cutting forces add to the friction from weight.

Slowing the cut helps, and I will let someone with a standard buddy speak more on the speed/weight issues. That makes smaller chips, so I recommend you try the shallower cut depth.

Also use your sharpest newest bits which will have the lowest cutting forces, that might help also.

That is exactly the situation the alpha systems take care of, they detect that the weight has caused a loss of accuracy and add additional steps to correct the error. That is of no concern if you dont have one.

My buddy 32 is an Alpha, and I haven't ever seen missed steps from weight with any of my powersticks. I have had it fault when something is binding, but it detects the error and shuts down the driver.

You might ask SB tech support what they have experienced as a practical weight limit. There is no set number as it depends on so many factors.

If I had a wish list item for future shopbot development, it would be a %power readout on each axis to let me know how much I could increase the depth of cut without stalling the motion system at the weight of part I am cutting.

Our buddies are more sensitive to this than the gantry systems, as the part weight has to be accelerated back and forth all the time.

Hope that helps

D

[Brady Watson]

Get your calculator out and do the math, BWC DualVee Catalog PDF pp26-27, direct download:

http://free.yudu.com/item/embedded_reader/338626/Complete-DualVee-Catalog-Rev.-05-11

Early BT32s used #2 wheels. Late use #3 wheels.

-B

[mikem]

Thanks. I'll need to brush up on my math a bit.
The explanation I got from tech support is that there are many variables to consider and the best thing to do is test for myself. The question seemed to be in using the buddy standard vs. the alpha. Anyone have experience with buddy32 standard and stalling the x movement ?

[Brady Watson]

Thanks. I'll need to brush up on my math a bit.
The explanation I got from tech support is that there are many variables to consider and the best thing to do is test for myself. The question seemed to be in using the buddy standard vs. the alpha. Anyone have experience with buddy32 standard and stalling the x movement ?

As with anything else, there are 'seat of the pants' (literally!) ways to test. After you make sure your fat butt isn't going to topple over the entire machine onto yourself(!), lean on it - progressively putting more weight on it until you can sit on it - do what is prudent - safety 1st! You may also want to put some gym weights on there and test the performance of the machine that way.

If you do encounter stalling, you can tweak the VR to make ramps longer, giving the motors more time to accelerate to cutting speed, or just lower your cutting speed. I would be more concerned with table/bed deflection than not enough motor power. Your MS and JS will influence if you lose steps while operating with a heavy load. Inertia is really what you want to measure - throwing around a lot of weight will affect both accel and decel of the tool & abrupt changes in direction is where the issues can occur.

It would be helpful to explain what you want to do, as this would shed some light on your specific challenges.

-B

[mikem]

We're in a high school shop. I'm looking to cut parts from sheet goods as well as be able to clamp smaller items that worked on the 24x32 cutting area.

I like the table setup that Russ Wood posted. Offers a lot of clamping opportunity. When I started talking about this process for my buddy with tech support, that's when the weight concern came up. Too much mdf for the buddy?
Is that style table too much? I like the t-track configuration.

I appreciate your willingness to point me in a good direction.

[Brady Watson]

Mike,
I think that if you have the outfeed rollers in place, you should be in good shape. Remember, all the cutting is going to happen in that 24x32" area. Granted, there is some deflection and more fluxuation in the table than a gantry type tool, but it is not unreasonable - ShopBot would not sell a powerstick to you if they thought it wouldn't work within the realm of what is considered reasonable for a CNC tool.

I think you will be fine cutting materials and using appropriate hold down methods consistent with what you have seen others do. I would however be hesitant to recommend the powerstick if you were milling non-ferrous metals or a project where precision is paramount. Your setup should handle just about any sheet goods or lumber that you can throw at it.

-B

[mikem]

Thanks Brady.

I'm still getting used to setting speeds.
Increasing the bed to 44"x 10' with a 32"x8' cutting area does add more weight for the x axis motor to carry. I did ask before buying if the 10' powerstick was a good match for the buddy. So I bought... The caution flag was raised when I mentioned adding the full sheets of mdf as the base table and sacrifice table. When I heard that I wanted to check with those with experience to hopefully avoid a few problems.

The part that I found a bit surprising is that tech support didn't have an "approximate" weight to go by.
Are there only a few who put an 8' powerstick on a standard buddy? So I guess what I'm seeking is to understand the "reasonable CNC practice" for a buddy... I am still on the early side of learning the process.

[Brady Watson]

Mike,
I think you just have to leap in with both feet and try it. There are too many variables to calculate between the weight of the table, material and additional friction from overhung load, and variable cutting force against your material to be cut - to give you a hard number.

The only thing I could say is - run it until you lose steps and then back it off. The worst thing that could happen is that you might lose a few steps and mess up a project, before you make adjustments so it doesn't happen on the next one. You are not going to hurt the Bot...

-B