Cold garage

[banderson]

Hello everybody - first post.

Purchased a PRS standard last week. Waiting on it now - should be here middle of March. I willl be putting it in a garage and mainly using it for wood signs to start with. My garage is not heated. Will it be an issue if I am using a torpedo heater now and then until spring? Not sure if machine will flex or move causing issues?

[billp]

Bret,
Depending on what you mean by "now and then" the biggest issue might be that You and the heater will be competing for the SAME air.....
I recently bought one of those "Amish style" electric heaters with a remote control for my garage, and now I can 'pre-heat' the garage for a few hours before I go out there to work on my boat project. Factoring in current electricity pricing in my area it costs me abut .75 cents to do this.
I used to have the "salamander" style of heater I believe you are speaking about and it would quickly use most of the oxygen in the room. Cracking open a door/window is self defeating in this case because you then allow more cold air to enter.
Unless you are going from a meat locker level of cold, to tropical I don't think you will see a significant change in your machine.

[Rob Gunn]

Bret, I am in SW Michigan and have my PRT96 in a mostly un-heated shop. I do heat it on weekends when I have more time to spend but during the week it is cold. I can say that I have never had any machine issue due to the shop being cold. As a matter of fact, the guy I bought my ShopBot from had it set up in a unheated garage and I asked him the same question before I bought it and he told me he never had any issue. I may be wrong but I have always felt that moisture and humidity are a much bigger issue. As we all know, wood will swell with moisture. All we can do is re-surface the table as needed.

[dana_swift]

My shop varies from about 40 degrees to roughly 90 when the outside temperature is from -10 to about 110 (the typical extremes here in Tulsa.) So my bot experiences a 50 degree temperature range.

The materials the machine is made from is mostly aluminum whose temperature expansion coefficient is 12.3E-6. So:

0.0000123 * WorkingGantryWidth * TemperatureChange = TotalWidthChange_inInches

Same formula applies in the GantryLength which will be another number.

I have the advantage of a BT-32 which is a very small machine so the total variation is proportionally smaller. But accuracy per inch, is the effectively the same for all the current (non-desktop) shopbots, as they are made from the same aluminum extrusions.

The worst dimension error for my gantry (34") is:
.0000123 * 34 * 25 = 0.010"

That is because I set everything up at nominal temperatures, so my calculation is based on being 25 degrees away from my setup-temperature.

However: this does not mean you cannot cut to 0.001 or 0.002 at any temperature. At most you would need to adjust your settings to correct for the situation. I dont bother. A hundredth of an inch is good enough over 34 inches for me.

Remember that your materials are usually reacting to the environment more than your bot will. Even though the thermal expansion coefficients of wood is much less than aluminum, the effects of humidity are substantial.

Plastics like HighDensityPolyEthelyene have a TEC of around 60.0E-6. Much worse than aluminum.

Hope that gives you some guidance as to what to expect.

My suggestion- get your bot. Set it up, and expect to be amazed!

This engineer is stepping away from the lectern-

D

[banderson]

Wonderful input guys. Thank you very much!!!!!

[chiloquinruss]

If my shop has been unheated for some period of time I turn the Bot on and run my table surfacing routine without a bit in it just to exercise and warm up the motors and the of course the spindle. Don't know that it is necessary just something I do. My temps range from a cold of 25 to 30 to a high of 90 so not to bad. For me personally if I can't see my breath then shop is OK to work in! Russ

[cowboy1296]

My response is just an echo of what has already been posted. I am in the moutains of Colorado. My garage is insulated and never gets below 47 with the door closed. When I work I turn on the heater for about an hour which takes the chil out. I use to work with the door open and remember once the temp hitting 25. It seemed to work just fine. naturally i have no humidity.

[myxpykalix]

This was my concern when i got my bot 6 years ago, and i thought "should i insulate or wrap the control box"? but the answer was No...
I have a rocket type heater that i fire up in an uninsulated shop and in 5 minutes i'm working in a tshirt when there is snow outside. The metal of the bot is still as cold as a "witches t*t" but it warms up after a while but expansion/contraction isn't something you need to be concerned with.

[MogulTx]

My biggest concern was that my previous bot controller was not liking the heat this past summer. I insulated the wall behind where I hung the new one... but I just wear a jacket and work gloves when it is cold- and a light shirt when it is hot- and don't pay attention to the temperature! Thus far, my new Alpha has been accurate, accurate, accurate.

[rcnewcomb]

Depending on the humidity in your area you may have to pay attention to condensation when the shop is cold.

But I've started the Bot at well below zero temperatures and the Bot was fine. The operator, however, began complaining after a bit and would wander back up to the house from time to time in order to get warm again.