Shopsmith Forums

So, for the first time, I went to hook up an SPT, the belt sander, and found that one of the drive hubs on the headstock had 4 grooves as called for and the other had 5 groves. Of course, the 4 groove was on the lower shaft and I needed it on the upper. So, I changed them and found that the 5 groove needed to slip through the vent plate a bit to get most of it on the shaft.

All of this generated some questions. First, the 5 groove hub is really for use on SPT isn't it?

Second, I need some hub on the lower shaft to act as heat sync right?

Third, I will buy a new headstock drive hub, but for now is there enough mass in the SPT hub for use as heat sync?

Next, are the drive shafts that much different in their protrusion from the headstock? My upper shaft has at least a half inch more sticking out of the headstock than the lower shaft.

If you get a new power coupler kit you get two coupler hubs to mount on the headstock, both are 4 notched, one has solid end and goes on the bottom the other with is open with a neck on it goes on the top.
See
http://www.shopsmith.com/ownersite/cata ... oupler.htm

Each SPT comes with its own 5 notched coupler hubs.

Sam
I am 100 miles from the shop right now but if you look at the drive shaft you will see that it is marked as to which goes to the headstock and which end gors to the SPT. IIRC the five splined end goes toward the headstock. The 4 splined hubs are for the SPT's. However the hubs for the SPT's may have different bores. I think the one for the belt sander has a 5/8" bore and the others have a 1/2" bore so the hub you have with the 4 splines that you can fit on the headstock is the drive hub for the belt sander. It is OK to use it as a heat sink and I believe that there is enough mass there to do the job.
The longer hub is usually use on the upper shaft and the only SPT used on the lower shaft is the jointer. Yes the upper shaft does protrude further from the headstock.
Remember that the lower shaft runs 60% faster than the main spindle.
Bill V

Ed in Tampa wrote:If you get a new power coupler kit you get two coupler hubs to mount on the headstock, both are 4 notched, one has solid end and goes on the bottom the other with is open with a neck on it goes on the top.
See
http://www.shopsmith.com/ownersite/catalog/powercoupler.htm

Each SPT comes with its own 5 notched coupler hubs.

The headstock coupler hubs come in two different sizes(as well as other/earlier versions). The hub intended for the upper shaft is longer than the one intended for the idler(lower) shaft. The longer one would probably need to be mounted reversed to secure the setscrew on the shorter shaft.

If you feel a need for a heat sink, any hub would suffice.

Ed in Tampa wrote:If you get a new power coupler kit you get two coupler hubs to mount on the headstock, both are 4 notched, one has solid end and goes on the bottom the other with is open with a neck on it goes on the top.
See
http://www.shopsmith.com/ownersite/cata ... oupler.htm

Each SPT comes with its own 5 notched coupler hubs.

Thanks Ed.

When I was looking at this page earlier, I did not realize the upper and lower hubs were different. I thought I was seeing a hub at each end of the coupler. The page has Drive Hubs listed, but when I select that it does not indicate whether it is an upper or lower, only that you order a separate part number if want a set screw with it. So I did not know the the upper and lower hubs differed.

So what I have mounted on the headstock is a lower shaft hub, now on the upper shaft, and an SPT hub. The coupler is currently fitted on the SPT's hub on one end and a drive hub (from the lower shaft mounted on the upper shaft). It looks like it would work until I can get the upper drive hub. Right?

wa2crk wrote:Sam
I am 100 miles from the shop right now but if you look at the drive shaft you will see that it is marked as to which goes to the headstock and which end gors to the SPT. IIRC the five splined end goes toward the headstock. The 4 splined hubs are for the SPT's. However the hubs for the SPT's may have different bores. I think the one for the belt sander has a 5/8" bore and the others have a 1/2" bore so the hub you have with the 4 splines that you can fit on the headstock is the drive hub for the belt sander. It is OK to use it as a heat sink and I believe that there is enough mass there to do the job.
The longer hub is usually use on the upper shaft and the only SPT used on the lower shaft is the jointer. Yes the upper shaft does protrude further from the headstock.
Remember that the lower shaft runs 60% faster than the main spindle.

JPG40504 wrote:The headstock coupler hubs come in two different sizes(as well as other/earlier versions). The hub intended for the upper shaft is longer than the one intended for the idler(lower) shaft. The longer one would probably need to be mounted reversed to secure the setscrew on the shorter shaft.

If you feel a need for a heat sink, any hub would suffice.

Thanks for replies! I am getting some good nfo. I had no idea that couplers came in 2 sizes. I just checked and both the jointer and belt sander can use the one coupler I have. The Band saw is on a stand an does not use a coupler, so I don't need a coupler unless that is the only way to buy the upper drive hub.

BTW I don't feel a need for a heat sink...but I thought maybe the SS did:D

On reading replies again, I see that it is not coupler that come in 2 sizes, but the SPT Hubs. No wonder Murphy's law did not catch me on my coupler working.

[quote="saminmn"]On reading replies again, I see that it is not coupler that come in 2 sizes, but the SPT Hubs. No wonder Murphy's law did not catch me on my coupler working.]

Both spt and headstock hubs come in two 'sizes'. The spt hubs come in 1/2" and 5/8" bore sizes. The headstock hubs come in short(idler) and long(main) versions.

I wish I had read this post before pulling all the hubs off of accessories and thinking "what the heck" and I also wish the power coupler kit had as good an explanation on the ordering site, maybe with a friendly link to this thread. hahaha. But noooooo I had to sit there for a couple hours and puzzle it out on my own.

It is possible that Charlese explained it to me and it just went over my head though.

Really nice thing is when I put all these hubs back on the accessories I understand the big one goes on the belt sander, because the little ones won't fit. All of those go on the other accessories and I don't have any for the headstock. I know that because I don't have anything with 4 slots - big little, open or closed. Ordering this morning

Charlese will read this one and think "That's what I was tryin to tell ya:)"

Shorts

I used to be a computer 'over-clocker' - a person who manipulated clock speeds & other parameters to make a CPU operate at double its rated speed. The secret to success was finding a way to remove the excessive amount of heat created to prevent a thermal 'runaway' condition.

I have used all kinds of heat sinks- one of which looked like a bed of 3" nails. The nails or fins on a heat sink simply provide more surface area for the heat to dissipate. Couple that will fans or other methods such as refrigeration or water cooling, i.e. antifreeze are effective in cars, in high-power radar klystron tubes, whatever. Excessive heat is never desired.

I fail to see the benefit of a small hub on the idler shaft stub used on the idler shaft for the jointer, paint sprayer or compressor. The hub is so small, but it does have a little more surface area than just the idler shaft by itself. It might be more effective if thermal conduction paste was used. A white paste which is like silver anti-seize which gets all over the place when you use it.

The new Mark 7 comes a plastic shaft guard/protector which totally covers both the upper & lower shaft/hubs extending through the belt cover. I think this will block any air cooling or heat sink effect of the spinning hubs due to the lack of air flow/circulation. I like the plastic shaft guard because it protects the idler shaft from being knocked into the head stock, as well as protecting people from a 16,000 RPM rotating shaft…

I had never realized the hub was used by some as a heat sink.