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Posted: Sun Jan 03, 2010 12:17 am
by JPG
What is needed is dimensions, not pictures. Also notice that the cam follower has a 'tension' pin. I believe that is to allow the cam to both push and pull on the control sheave.
RE: tilting. It is not only the table that 'tilts' both ways, but the way tubes etc. raise in either direction. This allows the headstock to be located beneath the table when tilted to the 'left' and is the reason for forward and reverse . This setup creates the ability to rout/shape with the spindle below the table.
Posted: Sun Jan 03, 2010 1:04 am
by horologist
I suppose the plastic was used for economic reasons. Anyone know what kind of plastic it is? Are they really melting, or is the plastic breaking down with age (heat?) and crumbling.
I've heard this part mentioned before but have never seen it until this thread. My first thought on seeing the photo is that it should be possible to machine a replacement in metal. Considering the ever growing numbers of CNC mills out there I can't believe someone hasn't already done this.
If nothing else it should be possible to make a mold from a good part and cast a copy. Aluminum might not be strong enough but brass should be possible.
If any of you have a machine with a good part I would recommend making a good measured drawing and taking clear photographs at different angles. Be sure to include a scale near the part as you can get remarkably accurate measurements off the photo. The scale needs to be at the same level at the portion to be measured and the camera needs to be directly above the part.
As an example, I once had to determine the distance between two holes on a skin of an partially assembled airplane wing. One accessible on one side the other only accessible on the other. While waiting for the inspectors to design a tool to allow an accurate measurement I used the camera and a scale and was able to come up with a number that was 0.001" off from the later official number.
Troy
Posted: Sun Jan 03, 2010 4:14 pm
by mikemarkvii
horologist wrote:I suppose the plastic was used for economic reasons. Anyone know what kind of plastic it is? Are they really melting, or is the plastic breaking down with age (heat?) and crumbling.
I've heard this part mentioned before but have never seen it until this thread. My first thought on seeing the photo is that it should be possible to machine a replacement in metal. Considering the ever growing numbers of CNC mills out there I can't believe someone hasn't already done this.
If nothing else it should be possible to make a mold from a good part and cast a copy. Aluminum might not be strong enough but brass should be possible.
If any of you have a machine with a good part I would recommend making a good measured drawing and taking clear photographs at different angles. Be sure to include a scale near the part as you can get remarkably accurate measurements off the photo. The scale needs to be at the same level at the portion to be measured and the camera needs to be directly above the part.
As an example, I once had to determine the distance between two holes on a skin of an partially assembled airplane wing. One accessible on one side the other only accessible on the other. While waiting for the inspectors to design a tool to allow an accurate measurement I used the camera and a scale and was able to come up with a number that was 0.001" off from the later official number.
Troy
A very good drawing with all dimensions is part of the mark VII info pack that I got from shopsmith a few years ago. I think the parts list, owners manual, etc. was well worth the 10$ I paid for it.
The plastic looks the same as what was used on the coupler to the spt's. I have two that have not melted, somewhat worn but still being used.
mike
Posted: Mon Jan 04, 2010 6:50 am
by robinson46176
Someone (I believe on the west coast) used to sell a cast aluminum cam to replace these but I think he sold out and quit the SS repair business.
I think that SS originally used the plastic (pretty sure it is nylon) so it would have a slick surface. On a working Mark VII the speed control works quite nice and I do believe it was an improvement. No cranking, just reach over and turn the easy working dial a few degrees to adjust speed. An instant recall including a metal cam replacement just might have saved them at that point but that just was not done back then in such markets.
I keep reminding folks that the Mark VII "was" designed to be a big improvement over the Mark V. Too bad that it didn't get "refined" a little or that Shopsmith Inc. didn't pick it as the new base model when they started up. Of course I have no idea of how things stood at that time. I'm sure there were a lot of factors in the decision that no one will never know. I'm just glad that they started up with any model...

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Switching to a Mark V headstock only takes about 15 minutes but you lose several functions. I am just waiting to see what comes about with the new headstock.
Posted: Mon Jan 04, 2010 8:33 am
by dusty
robinson46176 wrote:Someone (I believe on the west coast) used to sell a cast aluminum cam to replace these but I think he sold out and quit the SS repair business.
I think that SS originally used the plastic (pretty sure it is nylon) so it would have a slick surface. On a working Mark VII the speed control works quite nice and I do believe it was an improvement. No cranking, just reach over and turn the easy working dial a few degrees to adjust speed. An instant recall including a metal cam replacement just might have saved them at that point but that just was not done back then in such markets.
I keep reminding folks that the Mark VII "was" designed to be a big improvement over the Mark V. Too bad that it didn't get "refined" a little or that Shopsmith Inc. didn't pick it as the new base model when they started up. Of course I have no idea of how things stood at that time. I'm sure there were a lot of factors in the decision that no one will never know. I'm just glad that they started up with any model...

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Switching to a Mark V headstock only takes about 15 minutes but you lose several functions. I am just waiting to see what comes about with the new headstock.
I'm taking this thread even further off track but....I fail to see how the PowerPro makes much of a change to the operational characteristics other than "more power/less current" and a "reversible motor".
I know that some do (
or think they do) but I don't need more power and I don't understand what I might do with a reversible motor except accidentally feed something the wrong way.
I already possess that "potentially hazardous" condition with the Crafter's Station. I've been told that this was one of the factors that made the Crafter's Station so short lived.
Posted: Mon Jan 04, 2010 6:05 pm
by billmayo
dusty wrote:I'm taking this thread even further off track but....I fail to see how the PowerPro makes much of a change to the operational characteristics other than "more power/less current" and a "reversible motor".
I know that some do (or think they do) but I don't need more power and I don't understand what I might do with a reversible motor except accidentally feed something the wrong way.
I already possess that "potentially hazardous" condition with the Crafter's Station. I've been told that this was one of the factors that made the Crafter's Station so short lived.
Yes, a reversible motor can be dangerious if using any item on an arbor that is not made for this type of operation. The arbor will have a tongue washer to prevent the nut and attachment from spinning off the arbor.
I see the main use for a reversible motor is when using the Strip SanderChisel Sharpening Attachment and only have one Shopsmith. Currently it is only usable on the quill side meaning you have to remove what ever you are turning to use this attachment. So far, almost all my customers have a second Shopsmith to mount this attachment on. I did a couple of reversible Shopsmiths for bowl and spindle turners as they said they want to reverse the object being turned for the final sanding.
If anyone has a need for a Shopsmith 3/4 or 1 1/8 HP reversible motor, let me know. I am constructing a motor rework and testing station in my shop and will offer this as an option later this year.
Posted: Tue Jan 05, 2010 6:06 pm
by tryinhard
dusty wrote:I fail to see how the PowerPro makes much of a change to the operational characteristics other than "more power/less current" and a "reversible motor".
I thought the PowerPro major improvement is speed--up to nearly 10K rpm without need of a speed changer.
Posted: Tue Jan 05, 2010 6:58 pm
by a1gutterman
tryinhard wrote:I thought the PowerPro major improvement is speed--up to nearly 10K rpm without need of a speed changer.
Also, IIRC, fewer moving parts to maintain (more electric parts to replace)!
Posted: Tue Jan 05, 2010 7:01 pm
by dusty
tryinhard wrote:I thought the PowerPro major improvement is speed--up to nearly 10K rpm without need of a speed changer.
Yes, you are correct. I mispoke. Speed is another characteristic that the PowerPro is being praised for and if you need that speed the PowerPro will most likely be a great improvement for you.
For the work that I typically do (these days), I do not need an increase in speed either.
That puppy has done fine work for me for nearly twenty years and I don't need a bigger and better Mark V now. Just continue to support my parts needs and I will be content.
Posted: Tue Jan 05, 2010 7:07 pm
by fjimp
Wow the longer shopsmith waits to intro the new headstock the easier it will be for us to justify what we are already familiar with. Jim