12-01-2012, 10:47 AM
Hi,
Thanks Mark. I did actually consider a motorised drive when I first installed these blinds but in the end decided to keep it simple. The blinds need to be fully adjustable which for me being a mechanical engineer complicated matters considerably; limit switches placed for fully open or fully closed would have been easy enough to rig up with a motorised geared drive but to start and stop the motor accurately in-between both limits would have been a lot more difficult for me to sort out. I had even considered the more ambitious approach of remote control. I'm just happy that the blinds are now fully adjustable by the turn of a crank.
I'm pleased to add a picture of the mounting/bearing block Mark and hope it clarifies the arrangement. A plain bearing is just that; it is simply a hole bored through material allowing a shaft to rotate within. The bearings used for these blinds are extremely simple; a short length of 1" square BMS (bright mild steel) was bored at 1/2" Dia to suit the roller spindle; fortunately this gave a nice free rotation but had the spindle proved too tight I would have opened up the bore slightly; the bore size is not critical as long as the spindle rotates without binding. A small diameter cross hole was added with countersink on the top surface to allow a drop of oil to be added. Oil impregnated plain bearings are readily available in the form of bushes; a suitable oversize hole is bored/reamed and the bearing pressed home but for this application I considered the 1/2" Dia hole through 1" thick stock would give many years service. Rolling element bearings such as ball; roller or needle would also work but increase the overall size of the mounting and taken to extremes even proper pillow block bearings could be used very cheaply; in this case the bearings are hidden from view so many choices were available to me but I chose my method because it cost me nothing as all the bits were from the scrap bin.
The actual bearing block mounting is also very simple as can be seen in the picture; it consists of nothing more than a bit of 1" angle iron welded into place with two drilled holes to give screw clearance. I believe when I initially set everything up I only added one screw per bearing and this allowed automatic alignment; once everything worked OK then the second screw in each bearing was added. The length of the bearing blocks was determined by measuring the rolled up blinds allowing a bit extra. All sharp corners were removed then the blocks were painted.
Bearing block close up.
Two couplers for the three blinds were required and these are lengths of stainless steel round bar stock bored through on axis at 1/2" Dia. The boring was done in the lathe and this was the hardest part of the project; I don't like working with stainless but as I had access to as much as I wanted from work it was free; if I had known whilst I was working I would have brought a large stock of bar ends home as these used to go to the scrap yard by the wagon load.
Next time you visit David I'll give you a demonstration of the blinds in action. Bron and I visited "Homebase" about twelve years ago and we bought the blinds as you describe; they had the plastic bead cords with the cheap nasty drive arrangement and the material was mounted onto cardboard tubes. All I retained was the blind material and the rest was binned. I have a good selection of drive belts both "A" and "Z" section that I've collected over the years and this particular belt just happened to be a suitable length so I made the pair of pulleys to suit it.
The only cost incurred was the initial purchase of the blinds. The entire drive mechanism cost nothing other than a bit of electric to drive the lathe and my labour.
Owning a lathe opens up a whole new world of experimentation and it can be pressed into service in the most unlikely places such as this project.
Kind regards, Col.
Thanks Mark. I did actually consider a motorised drive when I first installed these blinds but in the end decided to keep it simple. The blinds need to be fully adjustable which for me being a mechanical engineer complicated matters considerably; limit switches placed for fully open or fully closed would have been easy enough to rig up with a motorised geared drive but to start and stop the motor accurately in-between both limits would have been a lot more difficult for me to sort out. I had even considered the more ambitious approach of remote control. I'm just happy that the blinds are now fully adjustable by the turn of a crank.
I'm pleased to add a picture of the mounting/bearing block Mark and hope it clarifies the arrangement. A plain bearing is just that; it is simply a hole bored through material allowing a shaft to rotate within. The bearings used for these blinds are extremely simple; a short length of 1" square BMS (bright mild steel) was bored at 1/2" Dia to suit the roller spindle; fortunately this gave a nice free rotation but had the spindle proved too tight I would have opened up the bore slightly; the bore size is not critical as long as the spindle rotates without binding. A small diameter cross hole was added with countersink on the top surface to allow a drop of oil to be added. Oil impregnated plain bearings are readily available in the form of bushes; a suitable oversize hole is bored/reamed and the bearing pressed home but for this application I considered the 1/2" Dia hole through 1" thick stock would give many years service. Rolling element bearings such as ball; roller or needle would also work but increase the overall size of the mounting and taken to extremes even proper pillow block bearings could be used very cheaply; in this case the bearings are hidden from view so many choices were available to me but I chose my method because it cost me nothing as all the bits were from the scrap bin.
The actual bearing block mounting is also very simple as can be seen in the picture; it consists of nothing more than a bit of 1" angle iron welded into place with two drilled holes to give screw clearance. I believe when I initially set everything up I only added one screw per bearing and this allowed automatic alignment; once everything worked OK then the second screw in each bearing was added. The length of the bearing blocks was determined by measuring the rolled up blinds allowing a bit extra. All sharp corners were removed then the blocks were painted.
Bearing block close up.
Two couplers for the three blinds were required and these are lengths of stainless steel round bar stock bored through on axis at 1/2" Dia. The boring was done in the lathe and this was the hardest part of the project; I don't like working with stainless but as I had access to as much as I wanted from work it was free; if I had known whilst I was working I would have brought a large stock of bar ends home as these used to go to the scrap yard by the wagon load.
Next time you visit David I'll give you a demonstration of the blinds in action. Bron and I visited "Homebase" about twelve years ago and we bought the blinds as you describe; they had the plastic bead cords with the cheap nasty drive arrangement and the material was mounted onto cardboard tubes. All I retained was the blind material and the rest was binned. I have a good selection of drive belts both "A" and "Z" section that I've collected over the years and this particular belt just happened to be a suitable length so I made the pair of pulleys to suit it.
The only cost incurred was the initial purchase of the blinds. The entire drive mechanism cost nothing other than a bit of electric to drive the lathe and my labour.
Owning a lathe opens up a whole new world of experimentation and it can be pressed into service in the most unlikely places such as this project.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
