Heating Tapes for Machine Tools

The recent discussion in MEW regarding the problem of dew-point condensation in workshops and the effect of such on machine tools (to which I added my penny'worth) has prompted me to think of this from another angle. Rather than maintaining a workshop either above the current ambient dew-point temperature or reducing the workshop humidity to reduce the condensation problem - why not raise the temperature of susceptible machines themselves above the ambient workshop dew-point temperature. Lathes and Milling machines have large metal masses - which creates hysteresis problems when external temperatures change. A cold workshop-machine environment may not have condensation problems until warm air with higher humidity enters the workshop space. Small items will rapidly adapt to the new environment - but large machines will lag behind and provide condensation surfaces. Maintaining these machines just a few degrees above the workshop dew-point temperature would solve the condensation-onto-machine problem. Heating tapes are often used to stop items freezing - and I've found tapes that provide low Wattage outputs (12W per metre, 20W per metre). These outputs are similar to greenhouse heaters. An added advantage is that the machines themselves would act as "greenhouse heaters" in themselves providing heat to the workshop.

Has anybody had experience of using heating tapes in such a way - or am I just being a bit daft.

Just put a 60 watt bulb in the cabinet ?

Hello Colin,

Heating tapes have been used industrially for keeping critical pipework warm on chemical plants for decades to prevent the product within from freezing [a relative term of course for the materials involved]

The name Heatfoil springs to mind. In that case the foil is wound round the pipe and covered in insulation. Those I remember were all 240 volt powered.

What I didn't know was that these systems can now be had in what I assume is low voltage, which makes them a great deal more attractive in use. My only concern is how well protected would they be against the effects of sharp swarf. It doesn't though address the miserable working in cold workshops for the poor user, the machines will hardly be toasty warm.

Regards Brian.

Edited By Brian Wood on 18/04/2018 11:25:56

Adding to my post - I've just discovered heating mats for uses such as reptile tanks, pets, hydroponic growing for sale on Amazon. These may be a better option than industrial grade heating tapes. They are self-adhesive, waterproof, cheaper and easier to install than the industrial heating tapes.

Our electrical engineers used to put small heaters inside switchgear cabinets to stop condensation, works a treat.

For small applications you could use a power resistor bolted to the machine structure, something like this

**LINK**

No I don't know how big to make it!

OK if the machines are inside cabinets - my workshop just isn't big enough for cabinets. But nice idea - providing the neighbours didn't think I was growing cannabis in my windowed workshop.

Great idea - and I've got several of these saved from historic breakups of old electrical equipment. Will try them out. Their physical size is the problem - the heat will be concentrated over a small area which may take time to propagate through the machine which may cause differential expansion problems. You really need heating over a large area to avoid this - this is why the heating mats seem like a good idea. Anyway - I've bought one (250 x 35mm) and will comment once it arrives on whether they might fit the bill.

I keep my fermentations (25 litre buckets) warm with just a 10W pet warmer - it has a single wirewound resistor of appropriate resistance. The temperature is controlled by a ‘dimming’ vivarium temperature controller. Probably need rather more than 10W unless the drip tray is comprehensively insulated beneath but the controller is rated for up to 600W.

I somehow doubt many would have space to store drop-over polystyrene boxes over their machines (exactly what I do with my brews - and likely needed here). Alternatives might be rolls of insulation...

Compared with insulating and draught-sealing the workshop area, along with a suitable dehumidifier (run for an hour or so each day), heating individual machines seems fiddly - but everyone should look at their options carefully.

Keeping the main body warm with heating tape or cables might lead to the extremities getting too cold - chucks, tailstocks and winding handles, but still worth considering. The whole system design needs addressing very carefully, I think.

The heater is in the cabinet under the machine and you drape a cotton sheet and maybe wool blanket over the top of the machine. Well that's what I do for one machine, and that's with a dehudifier too. I put the heater on when it is already cold but a warm front is approaching with rain. It isn't necessary when the machine is hot and a frost is coming as the shed walls are coldest and then attract the moisture.

Harold Hall has some advice on his website pointing out that localised heating doesn't remove moisture, just moves it around. SO while your machines may be protected your metal stock rusts worse.

Not such a daft idea - there's a posting on another forum in which the OP describes exactly that scheme that he has implemented:

**LINK**

I'm sure I saw an article about mounting wirewound resistors to lathes for just this reason - it could have been either in ME or MEW, probably about 20 or 25 years ago or was possibly in one of the electronics magazines of that era.

The idea of using heaters inside/under machine tools has, I think, been discussed before in these pages. I use some little heaters from RS Components - Part no 360-4059 & equivalent. Although described as10W Enclosure Elements, they are actually self-regulating and the ones I have actually run at 18W. I have fastened two of them inside the bed of my lathe and they have completely eliminated condensation. I also have one fastened to a large chunk of aluminium plate which is wedged inside the base of my milling machine, a Sieg X2 equivalent. Here again, condensation is completely eliminated.

In addition to the heaters, I cover both machines firstly with some cloth, and then with some plastic, the idea being to prevent heat loss.

It has to be admitted that there is a cost in electrical terms, but compared to the cost of the machines, I think it's worthwhile.

Although the ones referred to above are 10W rating, there are other wattages available.

I also use a heating mat from a fishtank - about 450 x 300 mm with a sheet of aluminium on top of it, on which are sat two chucks, a faceplate, a second cross-slide, and a vertical slide - all for the lathe. Again, the tooling is covered by an old nappy to try and keep heat loss to a minimum. And again, rusting and condensation is completely eliminated.

In respect of the metal stock, I keep mine covered in oil, which although not perfect. does help in reducing rusting.

Regards,

Peter G. Shaw

We used Raychem heat tracing where required on site.. Other places where I have worked utilised steam heat tracing to the same effect...

Anti condensation heaters can usually be purchased from electrical wholesalers......

Edited By John Rudd on 19/04/2018 07:18:41

Thanks for all the suggestions. I did do a search of the forum before posting but nothing came up.

This all came about through building a new workshop at the bottom of the garden during those recent cold and wet months of Jan-March. I modified the 12 x 8 wooden shed from Dunster House with polystyrene insulation to all walls, doors and roof, all surfaces then covered with heavy duty polythene sheet vapour trap and then complete hardboard covering on top of that. Much advice was gained from MEW's bookazine on creating and equipping a workshop.

But the build, inevitably during this wet period, introduced moisture into the interior space as I made stand-alone benches and shelves, etc for the equipment - mostly through walking the moisture in on shoes. Now the good weather has arrived, the shed interior will dry out to ambient levels of moisture. I then plan to use a low power greenhouse heater (30W) as a continuous shed heater and use Aero 360 Moisture absorbers to dehumidifiy the air continuously. But with the large thermal mass of lathe and milling machines, early morning hysteresis effects might still allow condensation onto the exposed surfaces - so keeping those machines slightly above ambient internal temperature might help.

I take the point about the other metal items around the workshop - and I may well position the greenhouse heater in close proximity (or even thermally in contact with the storage box) to those items. They should then act as a storage heater as well. Compared to the electricity I use for the rest of the house - even a few more 30W greenhouse heaters (probably on daily timers) will not make a lot of difference.

As my workshop is a combined metalwork - woodwork area - a problem I now face and need to resolve is dust. The workshop is arranged so that all the metalwork machines are at one end - and the woodworking machines at the other end. Simple curtains spring to mind - but there may be better solutions that MEW colleagues might like to suggest.

Following my purchase of a "Root-It" horticultural heating mat, I did a little experiment:

Placed the 9W "Root-It" horticultural heating mat (25cm x 35cm) below my Lathe (but not in contact with the lathe) and covered the lathe in a thin cotton sheet. Left the adjacent Milling machine without a heating mat and uncovered. Left the workshop to acclimatise over 24 hrs. Then applied a thermocouple to the vertical column of the milling machine - which recorded 14 deg C. Applied the thermocouple to the bed of the Lathe - recorded 17 deg C. So looks like even a low wattage mat and slight insulating cover has a positive effect in raising machine temperature above the ambient workshop temperature.

Green house heater 60w per foot

These type of curtains would be quite effective at dust control and allow free movement. If the wood shop is not being used then they can roll up out of the way.

Mike

Edited By Mike Poole on 24/04/2018 14:33:21

I have a home made wooden shed built more than 30 years ago as a workshop and have a de-humidifier running in it from mid September to early May and it keep thing rust free.I give the lady neighbours the water collected for use in their smoothing irons, so they are happy. De-humidifier do not use a lot of electricity (I have a KWH meter) and they do generate a small amount of heat. The shed is cosy when I walk in on a frosty morning with my insulated boiler suit and woolly hat on, ready for another day of happiness. Remember you can't take it with you and why be the riches person in the church yard. John.

Or 'tracer tape' from electrical supplies company - used in buildings underneath insulation to keep pipes from freezing. An essential item if running condensate drains from a condensing boiler or lightly used water pipes through an unheated roof space. (insulation does no good unless you are introducing heat into the pipe via flowing water with a temperature above freezing).

You might want to incorporate a control function on this to have it kick in before the air temperature meets the machine temperature.

The added problem not mentioned above is that, when machine temperatures fall below zero, as warm air arrives the condensation seems to form ice crystals that penetrate through the oil film. Thin films of ordinary slideway lubricant and WD 40 do not appear to prevent this.

When expecting those conditions I apply 'dewatering oil' on places like chucks and slideways and it has been a great success so far in keeping rust at bay. It is quite a gloopy oil (more like hypoid gear oil) but I'm not sure where you can get it from in domestic quantities. I was lucky enough to be given a litre many years back and am cautious not to waste it.

I find Ambersil Corrosion Inhibitor really good too, especially on hard to reach places and small tools as this dries to a very thin film and is less messy. I find it far superior to WD40 and use it on alloy and steel parts of my kit car as well as in the workshop. It isn't cheap but a little goes a long way. I have a hand sprayer constantly loaded with this and it gets used pretty much weekly on something or other. I believe it is much used in the marine industry.

I suspect someone will be able to give greater insight and technical knowledge on these points.