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Alternative to PC based Cnc controllers

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Clive Foster11/01/2017 14:35:21
747 forum posts
19 photos

Do yourself and your tools a favour and spend a weekend gluing 40mm if Kingspan insulation to the underside of the roof.

Better to provide battens or similar positive support rather than trying to jam in or use glue. Kingspan and foam type insulation sheets seem to compress a bit over time so will fall out if jam fitted even if its almost too tight to shove in. Glue doesn't seem to last more than a few years, say 5 or so, against a condensation prone steel roof. Dunno if cause is the damp getting under, near impossibility of getting roof fully dry before sticking, difficulty of getting full glue line coverage as both roof and sheet aren't super flat or just movement as the roof expands and contracts due to sunlight heating. If it is expansion and contraction might do better with big blobs of silicon rather than glue as being a bit more flexible.

Gotta bite the bullet and re-do my glued on steel insulation in the shop and the jammed in Kingspan between the rafters immediately underneath my new roof. Both done by builder types, with my assistance, disregarding my opinion that the job wouldn't last. No fun in "I told you so" when it means a ton of work for moi to fix.

That said such insulation really makes huge difference. Maybe halves my shop heating bill compared to relying on the 4" of insulation in the walls. Similar effect on heat losses through the house roof. Post extension new roof area pushing double old roof area yet losses through new one are similar to, probably bit less than, old. No regrets from jamming my pedal extremity down and assisting that both be done.

Clive.

richardandtracy11/01/2017 14:39:36
avatar
351 forum posts
3 photos

John,

Would it were that simple. it's a 35ft x 15ft open sided shed that I've enclosed with a window wall made from pallet timbers & sheet plastic (cost me 2000 screws from Screwfix). It was originally a kennel for a dog breeder (the previous owner of our house), and was never intended to be anything other than an open building of comparatively short life. I replaced the corrugated cardboard & bitumen roof 8 years ago, and now at least it doesn't rain inside even if the condensation drips.

I am planning to move my cnc stuff into a small brick built granary dating to around 1890 when I have finished dry lining it. That will help the roof condensation situation, I agree. However I must disagree about the problem of dewfall inside an unheated building. If the temp reduces such that you get 100% humidity, dewfall cannot fail to occur. We experienced it in the granary last week (9" brick walls + insulated under the slate roof), foggy outside, it cooled off & we got dewfall in the granary as well as all our sheds & outbuildings. Same happened on my parents' farm in Devon, so it's not unique to Kent. Also, if you soak a machine tool at a low temp (say 0C) in an unheated building, then when the ambient air warms, condensation on the equipment is inevitable until the mass warms up. The only way of ensuring dewfall never occurs is to heat the place - not feasible in most workshops, so computer stuff will always be at risk if designed to be inside a house.

Regards,

Richard.

Martin Kyte11/01/2017 16:22:05
781 forum posts
2 photos

I suggest you don't turn your computers off.

At least you will have plenty of cereal ports.

:0)

Nigel B11/01/2017 19:21:30
330 forum posts
2 photos

Do these controllers support servo motors? encoder inputs? tool changers? 4th axis?

The 990T & TAC-1003T are both "open loop" controls that have Step/direction outputs only & no axis feedback provision. There is one analogue output & one encoder input for the spindle. They have a built-in PLC & come with a "standard interface" PLC program that handles a turret (presumably some sort of standard locally produced turret interface), two speed spindle gearbox switching & other, normally expected, functions.

I did find a PLC manual for the 990T, which showed (at a quick read) almost identical functionality as the Fanuc PMC K/L/M used in the 0 series controls (with which I am familiar), with the same signal addresses used (X for inputs, Y for outputs, F & G for NC/PLC communication, R for freely assignable flags/markers etc.), the same command set & function blocks etc. So pretty much any type of functionality that could be achieved with a Fanuc PLC would appear (at first glance) to be available with these - even the processing times (Level 1 program @ 8 ms) are the same. The bigger problem seems to be limited I/O - I didn't find if the 990T could be expanded, but the TAC-1003T mentions additional modules are available to give an extra 16 inputs & 16 outputs - not a lot in the greater scheme of things, but some of the standard I/O could be re-nominated from the as-supplied PLC program if not required.

From an axis drive point of view, Chinese brusheless servo drives seem to have the option of step/direction control as well as analogue speed control as standard. I got a Bonmet 3Nm brushless drive & motor for a project at work that had this. The drive also has outputs for drive error (loss of steps) and a 1 rotation pulse signal derived from the motor feedback encoder - the control has inputs for each axis for these signals, so the control gets to know from the drive if it has stalled & to give more accurate referencing. A sort of "part closed loop-ish" operation, but not the same as a "normal" closed loop on an industrial control. You could also use one of these controls with normal open loop stepper drives, though these would not have the "lost steps" warning or give as accurate referencing.

Still look like an interesting proposition, though.

Nigel B

BTW, the £17 USB CNC board from Ebay didn't turn up within the estimated delivery time (still hasn't) & was refunded. I have yet to get around to ordering another to have a play.

Bill R13/01/2017 06:12:58
1 forum posts
Posted by Jat Grewal on 10/01/2017 23:44:32:

John, no need to be sorry mate, everyone's views are very important and I myself started designing these after having too many issues with PC based controllers and I might have my own point of view but also need to have everyone's take on this.

If you can please spare a couple of minutes and share what you think would be a good price point for the units and also what you like and dislike about the units the this can really help us understand what you as a user want so that we can keep improving the designs.

Jat.

Some feedback for you.

I have little or no trouble with PC's in the workshop environment. Occasionally a keyboard gets some dust or swarf, but are dirt cheap to replace. I prefer a large monitor to the small screens used in the stand alone controllers usually mentioned here. I am very happy with the concept you have come up with. The one thing I would put on the wish list is a touch screen monitor in addition to a conventional keyboard. Keep up the good work.

Bill

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