Power Pro Case

[dusty]

Here's what is done on the motor pan for a Power Pro retrofit:
- No change to airflow slot
- Original power-cord hole becomes "not used"
- 3 of the 4 original motor-mount holes become "not used"
- 1 of the 4 original motor-mount screws is opened to a wider diameter, to accept the power-cord.
- Motor itelf is now mounted to headstock casting, not to "motor pan"

Thank you for the clarification and correction. My understanding of the enlarged hole was COMPLETELY wrong!

[charlese]

Today it dawned on me there may be another good reason why there is a bulge in the sides of the motor pan.

The headstock case must be drilled in three exact places on each side near the bottom. (Shopsmith furnishes a steel hole locating jig with the DIY model) These holes must be countersunk (carefully) without enlarging the holes. The countersinks hold the heads of the M6-1X10SFSC Screws (part 522659).

The purpose of these screws is to mount and hold the motor mounts to the headstock.

If these holes have been countersunk a little too lightly, the heads will stick out and push on the motor pan cover.

To fix this would be a bit tricky - since the the weight of the motor is on these 6 screws and the screws go into the aluminum motor mounts.

I would not try this without the complete instructions of how to relieve the weight of the motor when removing the screws in order to deepen the countersinks. The headstock must be vertical and the saw table reversed in the carriage. One also has to be VERY careful to not strip aluminum threads, and avoid galling.

In other words, unless you have the DIY kit (which includes drill bit and countersink bit and instructions - it is not a worthwhile undertaking!

P.S. - - Here's a photo of the screws through the headstock Thanks to nuhobby!!! https://forum.shopsmith.com/viewtopic.php?p=74479&postcount=61

[JPG]

Today it dawned on me there may be another good reason why there is a bulge in the sides of the motor pan.

The headstock case must be drilled in three exact places on each side near the bottom. (Shopsmith furnishes a steel hole locating jig with the DIY model) These holes must be countersunk (carefully) without enlarging the holes. The countersinks hold the heads of the M6-1X10SFSC Screws (part 522659).

The purpose of these screws is to mount and hold the motor mounts to the headstock.

If these holes have been countersunk a little too lightly, the heads will stick out and push on the motor pan cover.

To fix this would be a bit tricky - since the the weight of the motor is on these 6 screws and the screws go into the aluminum motor mounts.

I would not try this without the complete instructions of how to relieve the weight of the motor when removing the screws in order to deepen the countersinks. The headstock must be vertical and the saw table reversed in the carriage. One also has to be VERY careful to not strip aluminum threads, and avoid galling.

In other words, unless you have the DIY kit (which includes drill bit and countersink bit and instructions - it is not a worthwhile undertaking!

P.S. - - Here's a photo of the screws through the headstock Thanks to nuhobby!!! https://forum.shopsmith.com/viewtopic.php?p=74479&postcount=61

Makes sense! Grind the heads down! Remove them one at a time to grind external from the ss.

[charlese]

Makes sense! Grind the heads down! Remove them one at a time to grind external from the ss.

Grinding down the heads of those screws doesn't sound like something I'd try. Hate to weaken the heads of those screws. they hold a lot of valuable weight.

[JPG]

Grinding down the heads of those screws doesn't sound like something I'd try. Hate to weaken the heads of those screws. they hold a lot of valuable weight.

FWIW the part protruding above the top of the countersink is contributing little if any additional strength.

Now if the countersink was deeper and the heads went in further, that part in the countersink does add strength.

In other words, that part of the head that is not contacting the surface contributes little to the shear strength. Of course if the head gets too small,there are other factors determining the holding capability.

Well Mike does that pass the sanity test?:)

[jctorok]

Good morning all;
Thank you for the great discussion and points. The PowerPro is all boxed up waiting on a ride back to Shopsmith. The customer service rep was extremely helpful (Linda) and after seeing the pictures was a grand supporter of getting in corrected.

Initially, I thought I might DIY the panel but after some thought, I would not have bought that particular headstock at a store with the pan bowing out. So, why should I accept it that way. It was probably going to annoy me for the next 20 years if I did not get it repaired. Additionally, our warranty, guarantees against defects in workmanship.

I will let all know what it looks like on the return trip.

Thanks again all.

[JPG]

[quote="jctorok"]Good morning all]

I am sure we are all encouraged by the action of ss cs in regard to this.

Hopefully there are not too many with this cover status and future occurrences will be minimized/eliminated.

[charlese]

Good choice, Jerry! IMHO

[JPG]

Good choice, Jerry! IMHO

Since they offered that choice, I totally concur!

[horologist]

Better late than never?


I have no such trouble on my upgrade, but I was very careful to ensure the countersinks were deep enough.
While cutting the countersinks I did notice that I was creating what is known as a knife edge condition, a no no in the aircraft business.



A back of the envelope calculation, (sorry I’m too pooped to do anything more thorough)


For static strength, one must look to the weakest link. The screws are not high strength fasteners and probably have a shear value on the order of 1200lb.



The strength of the housing will be determined by the depth of the countersink and the ligament. (Distance between the edge of the hole and the nearest edge of the part. ) As the housing is cast aluminum I am estimating the strength here is on the order of 200lb - 300lb.
So from a theoretical standpoint you are better off filing the fastener flush than deepening the countersink. However, modifying fastener heads is generally not a good idea and in reality this isn’t that critical an application. If you neglect the benefits of the belt tension and assume the motor weighs 60lb then you are talking about a load of roughly 10lb per screw.

I’m glad Shopsmith is taking care of the problem and hope you get your new machine up and running soon.

Troy