Dempster 6-No 12 - Rookie build

[tholt]

Hi Folks, We recently picked up an old Dempster 6-No12 windmill. Our first windmill, so be gentle! We plan to use it as a decorative windmill on our property, so we are targetting functional repairs moreso than a 100% vintage correct build. I have no idea on the age. The only info I have found says these mills were produced from about 1925 until Dempster shut down in 2009. Is there anyway get a more accurate estimate on age? The previous owners acquired it about 25 years ago, never completed rebuilding it and did not know the previous history.

The motor had been restored, and the blades are in great shape. The steel tower is 24' and in decent shape, but it appears to be a random tower that has a few parts missing and a few odd parts that don't see to match or fit. Only one of the 20ish brace wires seems to fit and there is an extra storm stay that doesn't seem to match. It is also missing the stem pipe...

A few main questions, what is the recommended replacement for the brace wires? How hard is it to twist my own, or should I save myself some trouble and just use some turnbuckles and steel cable or rod?

Second is the stem pipe, is there any reason I shouldn't just use a piece of 2" steel tubing? Is there anything special about an original stem pipe?

(Sorry for the random upside down photos)

Tom

[CTXmiller]

Welcome to the forum.

Others are much more knowledgeable on the forum when it comes to Dempster, but the brake is a post (+/-) 1932 braking system. Dempster had a band brake prior to the brake I see on your Dempster #12, which was older.

I’ve never twisted my own wires and I’d be more likely to go back and use rod and run the rod through your L brackets and thread the end of the rod and put a nut on the threaded rod to tighten tension. I’ve never seen a L bracket on a Dempster tower, but have seen them on other manufacturers towers such as Axtell, Butler, etc.

The extra storm stay that I think your referring to is the pump rod guide for the pump pole.

You’ll need a pullout tube for the mast pipe to turn the windmill on and off.

Others can provide more educated observations.

Your gear box looks to be in great shape. The nut on your hub, most that I’ve seen are a castle nut and pin and not just a conventional hex nut.

[mtblah]

Tom , I garee with Michael's observations , the "extra" is a pump rod guide as most rods were square .
I have twisted a few wires with a little sucess , about half come out the right length but all need some sort of tightening Nut & bolt on at least one end
You can buy wire at the local Tractor Supply store , GUESS at how long a piece of wire to cut , fold in half , clamp the two loose ends in the vice , a large round shaft screwdriver in the loop end and start twisting , start with a small piece just to pratice and see how the wire responds ,
the complicated part is how much the wire shrinks as you twist .
There are guys on this site who are significantly smarter than I am who could calculate that factor , not me .
Everything you have posted appears to be in great condition , do you have someone to pick up the tower when to get ready to stand it up ?
Digging the holes is just plain old hard work but the leveling is the portion that takes skill & patience .
Mike B
New Braunfels TX

[mtblah]

Tom , you have a neighbor just east of you in Manor who has extensive windmill experience . Has now switched to wind electric but his history was origionally water windmills .

[tholt]

Thanks for the quick replies guys!

I think the suggestion of the threaded rod and L brackets sounds like the best solution for the cross braces. I guess I need to do a little more research on the make vs buy decision on the stem pipe/pullout tube.

The lower pump rod guide assembly does not fit this tower, I would have to drill some extra holes to make that fit. I will save that until I get everything together to see if it makes sense to install.

Tom

[Wayne]

When Windy Bob answers he will have a lots of knowledge. Dave Straub from Syracuse Ks. just down the road from where it was built knows Dempster's inside and out.

[windybob]

The mast pipe, (neckpipe) for 6 and 8 ft #12 Dempsters, is 1 1/2 inch pipe. They used sch 60 pipe, but the replacements ar usually sch 40, or just plain black pipe. There is a slotted bushing in the bottom, that lines up with a guide hole for the line-up pin at the top. this bushing is for a pull-out tube to control the off and on to the mill. On the pull-out tube, there is a swiveln and that also has holes for the pull-wire, that goes the the bottom of the tower to operate the off-on for the mill.

The head is a later model, as they had major improvements through the years, since the 20's. Yours is the next-to-the- last rendition, and the last of the long line of #12 mills, the Dempster "12-B" model, was the very last one. The 12-B was the regular #12, only a couple things changed for it. A spring behind the noseplate instead of the extention of the noseplate back to the outer bearing race, and a weldment instead of the casting for the lower pivot on the tailpin. Also was a minor improvement with the spacers on the mainshaft, for oiling I believe.

[windybob]

Parts for your mill are quite common, and easily found. If you are going to use it for a spinner, also install a pumprod, to keep the yoke centered above the opening in the head to avoid a possible oil leak, and possible hitting of the yoke if it leans to one side or the other. Tht's a fairly close fit anyway.

The tower is most likely not a Dempster, but that's fine as long as the hardware on top accepts a Dempster mill, which yours does. You could also shorten the tower to show off the mill closer to the ground. I have 6 footers on 15 to 20 ft towrs, and they look fine. So, your list starts with anchors for the tower, a neckpipe, a pullout tube, a pullout tube swivel, a brake handle, # 9 wire, a pump rod, a quart of oil, extra boxes of SAFETY ( for erecting) and plenty of patience.The pump pole guide is optional, depending on what you desire at ground level. Also, throw in a couple of ladder sections for the tower, and all the X bracing needed.

[windybob]

Oops, almost forgot the turntable top and bottom, and balls for it.

[tholt]

Long overdue update. I got her up about a month ago. It hasn't been totally trouble free, so I keep it locked down most of the time. The biggest problem is it tends to run too fast, this is just a spinner, so there is no load attached to the pump rod. I have no idea what the appropriate load should be, I am guessing 10-20 lbs? I have loosened the regulator spring but it is still running about 50-60 rpm in a mild breeze.

I did have a pretty major malfunction earlier this week where the stem pipe pulled out and the complete motor/vane assembly fell over and was hanging by the pump rod and pull out chain. The new stem pipe I purchased a few weeks ago was missing the hole that the Stem clamp locks into and I hadn't noticed that when I assembled it. Very fortunately the blades and vane were undamaged and I was able to straighten the pump rod and get it back up within a few hours. This time with the added hole in the stem pipe!

20230415_091940.jpg

Tom