Shopbot gets new life! Acorn performs magnificent.

[MattD]

Greetings fellow Acorn enthusiasts,

Like many of you, I earn my living working with CNC machines (mostly routers). We have a variety of routers, most of which run on Shopbot hardware and software. Earlier this year, our very large (5'x20') 2001 Shopbot PRT began to fail wildly. Sometimes an axis would stop moving or even go in the opposite direction. Sometimes there were communication errors. After trying to diagnose them without success, it was time for a better solution.

Here is the original V4G Shopbot control box. As you can see, it was enclosed in an ATX case, used a 63v torroidal power supply and a large breakout board for its Gecko 203V drivers. The drivers were oriented vertically and without heatsinks. An ATX power supply provided 5v and 12v power to the board.

I decided to strip whatever components I thought were useful from the existing control box. Mainly, the power supply and drives. I ravaged an old Denford control box as well for bits and pieces. I made quite a mess.

After a bit of cleaning up, things were starting to take shape

And eventually, this was built:

The PRT was never made to be incredibly rigid or move/jog/cut at fast speeds. That wasn't what we needed anyway. We needed our machine to handle very large files and cut for hours reliably. This Shopbot PRT, with the addition of the Acorn now runs better than it has ever had. It is rock solid and can run all day in and out without a hiccup. We're even running it on a PC that doesn't meet the full recommended specs! I'd like to mention also that Shopbot uses a MODBUS method of communicating with VFDs. Unfortunately, they really only support one model (Yaskawa) VFD and you can't change any MODBUS parameters. So if you had another brand, you were stuck without any sort of software speed control. Connecting the VFD to the Acorn for spindle on/off and speed control using the analog 0-10v and output relay was rather straightforward and added a capability that we didn't have previously. Thanks to Toaster (Eric) for reminding me to actually set Output 1 to spindleFWD. The machine is incredibly responsive now, more so than ever before, and the smoothing functionality has allowed us to control acceleration/deceleration/ramping in a way that is appropriate for that type of machine. I hope to create some videos in the future to help new users and those looking to convert over. I also want to thank Gary Campbell for berating me on a regular basis but also giving useful information haha. After the success we had with this upgrade, I would be quite excited to do it on my modern 4x8 machine and see what it can really do with some power behind it. I also have a smaller machine that would be a great candidate for a conversion. The reality is that this is simply a superior control system that has the functionality to handle everything we need while getting better, faster, and more consistent results. Another success story! I'm happy to answer any questions!

Thanks
Matt

[gerald martin]

Good job Matt. The Bot is a completely different machine with the acorn isn't it!

Gerald

[Gary Campbell]

Hey Matt...
Sorry I had to humiliate you into changing your controller. You can thank me later when you get the other 4 machines swapped over to Centroid Control!

Nice job on the swap over to the Acorn!

A wise man once (actually many more times than once) said: "Let's see some video of it cutting!!!" ~cnckeith

[robtown]

Thinking about either buying one of Gary's upgrades, or building one myself.

I have an old PRT with a 4G upgrade.

Looking at the Acorn wiring diagram for the Gecko 203V's I see the need for a "220 OHM Pull Up resistor".

Is that only necessary when you don't go the route of the DB25 connector?

And what did you use for your heat sink(s)?

[Sword]

Good job Matt! Turned a sows ear into a silk purse!

[Gary Campbell]

Rob...
Except in rare cases with the older DIY grade drives you will be using the DB25 connector. For a couple of methods look here at about 3:00 in: https://youtu.be/TLOtXTOSUWo

Of course I would like to sell a gazillion Acorn control boxes, but with that said if you decide to self build, there will be help here. Virtually every SB beta tester (a good number of their most knowledgable users) have Acorns, have converted machines and are successfully running ShopBot machines on Centroid Acorn and each and every one of them has reported increases in reliability, smoothness of operation and speed, while noticing less noise.

Remember... only the later ones to swap will NOT have a market to dump off their old control boxes.

[martyscncgarage]

Let's see a video of it and the control running!

[MattD]

Thinking about either buying one of Gary's upgrades, or building one myself.

I have an old PRT with a 4G upgrade.

Looking at the Acorn wiring diagram for the Gecko 203V's I see the need for a "220 OHM Pull Up resistor".

Is that only necessary when you don't go the route of the DB25 connector?

And what did you use for your heat sink(s)?

I can attest to the quality of Gary's control units. I bought one myself for my 2017 machine and it has performed great. I wish the acorn was available when I made the choice! If you have the time and ability to work on building a new control box or upgrading an existing one, I certainly wouldn't dissuade someone from giving it a go. However, if your income is dependent on your machine and want to make sure everything is going to work when you plug it in, then shooting him an email and exploring options is a wise way to go. I'm fortunate enough to have a bit of experience in the area and have built relationships with people (like Gary) who do this for a living so I can call for a lifeline when needed.

As for the 203v wiring diagram, clearly someone was able to figure it out the "traditional" way, so to speak and make it functional. However, from Gary's testing, he was able to get a cleaner signal using the DB25 out on older architecture drives. With that being the case, I'd recommend dropping the 15 bucks on a DB-25 breakout board with screw terminals. No soldering or resistors to worry about and the wiring is quite easy.

3 of the heatsinks were salvaged from an old Denford cnc router control box. The 4th was laying around in spare parts. I trimmed down the thickness on the 4th and drill/tapped them to mount the Geckos. Since you have a 4G upgrade, you're aware of the vertical installation of those drives on the breakout board. While they have the anodized aluminum back plate, they were never mounted in a way to dissipate heat. Since the older shopbots have motors that are under 2 amps, you could mostly get away with that. However, if you put any real load on those geckos, they can run HOT. You could probably get away without any real cooling measures (shopbot did), but I wanted to be more safe than sorry with the lengthy run times of some of our files (and we also suspected that some of our earlier failures could have been from heat). As it turns out, we can run all day now and both the motors and the geckos are just warm to the touch. You can find heat sinks online that would work or even just machine your own if you wanted to take a similar route.

Either way, you wouldn't be making a bad choice if you wanted to convert over. It is quite nice to not have phantom failures and comm errors 7 hours into a 3D job.

[MattD]

Let's see a video of it and the control running!

I'll get on that one. Bare in mind, I'm not sure it's going to be the most interesting video as we have strapped it down pretty hard in terms of it's accel/decel/move/jog rates to keep it running slow but steady. It is after all a 17 year old machine that was delivered as a kit back in the day. However, It's all we need from that machine at this point. Now, if I happen to get a hold of another acorn and convert my new machine, that could be a fun video to watch. I could even compare the same file against a Shopbot Alpha that's in the shop and see what happens!

[robtown]

Done and done. Hold my beer...

I've decided to forge ahead and build one myself.
My apologies to Gary for the head fake as I've inquired with him about his upgrades a couple times over the last years.

The fact is, my machine is not a production machine nor do I depend on it for much more than a theatre set a year for my daughter's drama club and an occasional small furniture or sign job here and there.

Being a tinkerer, this is an "it's about the journey, not the destination" thing for me. And the more I read here, the more I want to jump in myself.

Two things I've never done much of... or very well, electronics and carburetors. I'm a software guy and a tinkerer, but I think I can handle this.

The plan:
I think instead of cannibalizing my existing control box, I'm just going to build a new one. That way if it works I can either sell the old box or keep it in case I ever need it. Plus, my PRT box has the original 48v power supply in it, not that sweet torroidal 63v supply, so basically all I have to repurpose out of my old box is an underpowered power supply and the Geckos. So...

1. I've ordered 4 Gecko 203v's, a DB25 breakout board and the Acorn kit.
2. I think I will order a 63v torroidal PS from Antek. I see the Geckos have a rating of 80v max, but I figure why push it. If I'm reading things correctly, more power just means more speed (and more heat)... I want better cuts, not faster cuts. Or should I get the 80v?
3. Finding an enclosure has been a challenge... I guess I'll either pull the TIG out of storage and fab one from alum or just buy a swank gaming case... (open to any suggestions here... eBay has a couple potential enclosures, but the shipping for all of the ones I've found is more than the cost of the enclosure itself)
4. I'll pick up any incidentals like wire ducting, cooling fans and distribution blocks as needed (not exactly sure what I'll need yet)
5. As to the heatsink(s) issues... I can buy the Gecko heatsink for 74.00 that only holds three 203v's, or I have plenty of 1/4" alum plate laying around that I can make 4 mounting plates (heatsinks) with, or I can buy 4 cpu heatsinks.
6. I have a couple Win7 laptops laying around that I can update to Windows 10, or maybe I'll check with Gary to see if he still has any of those optimized Lenovos for sale.
7. Get everything running/turning/spinning on the bench, then transfer over to the PRT
8. New steppers? (or is this something I should be considering now... not later?)

"Everybody has a plan til they get punched in the mouth"

Please feel free to poke holes in any part of this plan, or alert me to any gotcha's. I'd rather know now, not later...