Start Point Changed on started Project

[jkaras2000]

Hi All: I have a mantel on the bot this weekend. I started roughing it, and a few hours later noticed a missing com notice. I ended up doing a UR or User Reset, because the servos were making that horrible chattering sound. Only problem now is, when I load the roughing part file now, the bot wants to start the roughing tool path several inches to the left of the workpiece. Any one have any ideas how I can get the bot to start where it did previously? Or have I made a fatal error? Thanks Joe. :cool:

[Steamplates]

I've had lots of problems with that Joe, so I sympathise.

My success at solving the problem has been mixed, right from absolute saving of the job to having to throw it in the bin and begin again.

To get Z Zero back is easy enough but X and Y will be the problem. Did you begin from a known, fixed point you can get back to? Have you machined anything that you can 'pick up' on, i.e. if some feature were known to be (say) 20" X and 10" Y away from the lost XY zero so you can work backwards?

This is much like that basic maths stuff at School, 'Find X', but not the X we are used to. Even if you can only get back one co-ordinate (say Y) from a groove or something, you will be half way there and only need to guess the other as best you can.

When you think you are close, cut air just over the job to see if the new zero looks right, say by using a profile cut (in air) around the outside of the work half done. if the tool traces that faithfully you're back in business.

Another idea is to draw (in your software) something like a circle in the waste around the job, a fixed distance X and Y from the centre of the job you were doing. Centre that circle with a small drill in the waste and then measure the actual distance of the circle's centre to the already done work centre, allowing you to adjust your new XY zero by adding/subtracting from the new XY zero as shown on the screen.

I have to say (not much help to you today) that I am firmly convinced that the very next thing I need to add to my set up routine is to always begin with the tool at a fixed, repeatable XY position before the inevitable happens, sometimes right in the middle of machining £100 or so worth of Brass. If that isn't possible, I might choose to begin by touching a cutter in the waste, noting the co-ordinates from XY so I can work back if required.

Prevention is the key, in a perfect world it would not be needed, but the world is not so...If nothing else there is always the risk of a power cut coming to spoil your day, so be prepared.

Good Luck

Steve

[jkaras2000]

Hey Steve: Thanks for the reply. I get a sense that you fully understand where I am at. Very frustrating to say the least. The culprit that got me into this situation was the nuisance of the "MISSING COM" message putting a spanner in the works. If it were not for the Missing Com popping up, I would have finished my carving and gone on to the finishing part file. However, I did do the following. When I created my Mantel, I took the liberty to vectorize just the circumference or the outside edge of the mantel file. I then created a part file of just the diameter of the work piece. I had it go down about an eight of an inch into a scrap piece of MDF. I then placed the mantel wood directly over the area that was outlined by the part file. I ran the circumference file again. I then placed the work piece directly over and on the circumference edge groove or carving. I was then able to run the roughing file to carve the mantel. This worked out great, and I would suggest others doing the same so you could alway place the work piece directly over the outside edge carving of the work piece, no matter where the bot dictates it should be. The file was running great, so problem solved. However, the "MISSING COM" popped up yet again. I think this is my new problem that needs immediate attention. If you or anyone else reading has some advice I would be eternally thankful for your help. SO, I guess I have solved one half of my problem at best. Regards and Thanks Joe :cool:

[Steamplates]

My machine gives me 'missing com' too sometimes. The worst occasion was when it re-set itself to XYZ zero 6ft or so down the board, when coming back up for a tool change it froze and did that. Nothing had been touched. Weird!

Only way to deal with it for sure is to always use a fixed and repeatable XY Zero point prior to cutting anything.

I am working on this. Look out for another mod.!

Steve

[jkaras2000]

I agree. I am a newbie with the machine, but am coming along. This interruption is stopping me dead in my tracks. Right now, it's not my prowess with software that is holding me back, but a hardware issue. I think the fixed starting point is key. I have read that folks on the forum have set up this starting point, and have even screwed down a fence to nest the working material against. Good Luck to you as well. Joe:cool:

[Gary Campbell]

Steven, Joe....
Do your machines have the proximity switches installed? These electronic switches serve 2 purposes.

1) they allow you to home the machine (set the X and Y zero) with an included routine (C2) and give pretty good results.

2) they act as limit switches to electrically stop the machine before it hits the hard stops. I like to use one on the Z also.

When there is a comm error, the computer portion has lost track of where the mechanical portion is. This is natural, as the computer has lost communication with the hardware. After a reset, you need a reliable way to reestablish the location for all 3 axis.

What may be unnatural is having more than an isolated comm error. These can happen from static discharge and as a result of low comm rates. Most non static comm errors happen due to low USB transfer rates or background operations in the control computer. The core architecture of some brands (read as Dell) will require the addition of a USB 2.0 PCI card to ensure proper comm with the control box.

Grounding usually solves the static portion of the equation. Doing a speed test and removing all software and uneeded services from the control computer usually solves that part. There are dozens of posts on this forum that explain both methods. The search function could be your best friend!

[jkaras2000]

Thanks Gary: Always good to hear from a seasoned Bot owner like yourself. Funny you mention the limit switches. I have them installed, but every time I try to set them up, the Gantry cruises right past them. I just found my spark plug gapper which has a 2mm gauge. I have to check them to make sure they are gapped properly. The manual states that they should be 2mm. I don't know if this is critical or not. It seems when I manually move the bot the limit switches seem to work fine. Only have the problem when I run the limit switch set up program. I ran a speed test some time ago, and it was at an acceptable level. I am using a Sony Vaio Laptop with XP or XP Pro. Do you think my laptop could be the problem? Should I switch to a dedicated desktop? I can check to see if any background programs are running which may be interfering with the program etc. I do not have dedicated ground to bot frame, and have been considering adding one for safety. My vacuum system is grounded, so that should be OK. Thanks Joe :cool:

[Gary Campbell]

Joe...
I have a couple of Viao laptops, so I dont think they have a comm bottleneck. What they, and most branded machines have, is a large number of apps added to "enhance" your life and their pockets. The one I use for a design computer at the shop had over 30 uneeded programs removed.

The most obvious things to disable/remove are windows restore, task scheduler, antivirus, screen savers, many printer softwares, any software that periodically checks for updates and automated support (Viao Care, etc). wireless internet has also caused problems. turn the network connections off.

The rest you get from the search engine :D

[jkaras2000]

Thanks Gary: I will do as you suggest. I am sure that there are programs running that don't need to be there etc. Any thoughts on why the limit switches are being passed by when I run the limit switch set up? Joe:cool:

[Gary Campbell]

Joe...
Make sure that the settings are as required for the machine that you have. A PRT has different settings than a PRS. Download tha manual for your machine to get all the settings correct. ShopBotDocs is a good place to find info

[srwtlc]

Joe,

Make sure that the limits are turned on under VN (Values Input) and that they are set right for the type of switches you have on your machine (NO or NC).

SF for file limit checking is another one that can trip a person up to, but also save a crash if your file is going to go too far.

[Gary Campbell]

Joe...
Another thing.... when running the SpeedTest, try all the USB ports. I have seen 20% difference between ports on the same machine.

Scott....
The NO/NC is pertinent, but the prox, if set properly, will function to home the machine even if VN (limits) are off.

[srwtlc]

Was pretty sure that was the case. Didn't know if Joe was going past them during homing or if he could make it do it manually.

[Steamplates]

Gary,

Than you for all this info, I will think about moving to XY zero set up using the prox. switches. Can they really be trusted to give perfectly accurate and repeatable results every time? On some of my work, if they were just 0.010" out on a reset, the job would be ruined.

Joe,

I might be more help to you this time. Just tell me first, how are you testing your prox. switches?

Regards

Steve

[Gary Campbell]

Steven....
I am sure that if set properly they can give the results you desire. How do you accomplish this task now?

[Steamplates]

Gary,

For work like this I have to say my Bot is amazingly accurate, allowing me to do jobs such as this when they are too large for my milling machine.

Plates like this are made in pairs by mounting them on the board, using their actual co-ordinates on the table to feed into Aspire. I use the 'centre of material' choice for XY location when making the Aspire toolpaths. I only get into trouble if XYZ - Z is lost and I forgot to make an XY mark in the waste metal so I can reset if required.

When I move on to the new 8 x 4 board work I have, several parts are cut out of that board. It is better for me to use X = 0.00 Y= 0.00 as my XY - Zero, so using the proximity switches to repeatedly and reliably reset XY - Z might be the best option in that case. If I could utterly rely on this procedure for the plate work as well, then I would be a lot better off.

Regards

Steve

[Gary Campbell]

Steven...
If, for example, you used the prox and X-Y zero routine, you could move to the center of your material, write those coordinates down, [Z2] to zero there and return to them easily if position was lost. Use of the prox makes the x & y as repeatable as you take care in their use.

Another method, my preferred, is to leave the X & Y zero as is and design your parts where you have placed the material on the table. This allows many of the built in functions of the SB3 software to do their job as designed. Many times I will cut index lines or machine a shallow pocket to hold these parts. Since the recess was cut from a toolpath in the design software, accuracy is maintained.

[Steamplates]

Thanks Gary,

I think I will follow your advice and begin working from prox. XY - Z and see how I fare. As a back -up I might still make a little former that fits over the XY corner of my table, not only to manually set XY - Z but to set up the prox. switches in the first instance, then everything will be repeatable.

I will get the prox. swithes to bring the spindle where I want it to be and then spot a hole in the plate, giving a hard record of where the prox. XY - Z zero is to begin with.

Regards

Steve

[jkaras2000]

Well Gary. Have to say many thanks to you. My bot is running a part file that is at 78% completion with NO NO NO MIssing Com ERRORS. It has not stopped once. I hope I am not Jinxing myself. I restored the VAIO Laptop with the system restore disks. I then deleted programs I was not going to use. I went into administrative tools and took off a lot of things that were set to automatic. I either disabled them, or put them in manual mode. I even was able to achieve a system speed of 75.4%. Everything overall is much better and working. I think I am well on my way. Thanks Again Joe:cool:

[Gary Campbell]

Joe...
Glad to see that you're working

[jkaras2000]

Hey All: Have to report that all is still working great. My xy Prox switch wires were wired wrong. I reversed them, and they work like a charm now. The computer help that Gary gave me has cleared up all Missing Com Port Errors I am glad to say. Just wanted to let you all know that my bot is working great and I appreciate all your help. Thanks Again, you guys are the BEST. Joe:cool: