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Resurrecting a Takahashi EM-100 mount

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#1 PJ Anway

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Posted 25 October 2009 - 04:15 PM

I recently purchased a Takahashi EM-100 mount off of the Internet. Takahashi made these mounts in the 1980’s and mine appears to be from the last year of production. It’s serial number is 9002 ( pic #1 )– which translates into the 2nd mount made in 1989. I owned one of these mounts years ago that had a serial number of 6297, which means it was the 297th mount made in 1986. That one was “Takahashi gray” ( pic #2 ), so they must have changed color to “Takahashi green” somewhere in between. They are a solid mount and according to the Instruction Manual, “the maximum load carrying capacity of the EM-100 mount is approximately 30 lbs.”, though most (and I would agree) feel it is more like 25 lbs. I purchase this one as a backup to my workhorse mount – a Losmandy G-9.

I knew when I purchased it that a "restoration" was in the mix. The seller pretty accurately described the shortcomings and I point them out in the pictures, but after unpacking it, I found a couple additional ones. As shown in pic #3 , the counterweight shaft was missing a retainer nut and the large slow-motion knobs were missing; I knew this and I had purchased it without a tripod. However, I didn’t know there would be no counterweight. I contacted the seller and he said it was an “oops” on his part and that he would be sending one along shortly. In pic #4 there were also missing cover screws for the R.A. clutch cover, which I also had been told. But added to that was a broken slow-motion shaft on the R.A. spur gear. The seller said that it was there when it left, so it must have happened in shipment. It is less that ¼” inch in diameter and so it’s not surprising that this could have happened; rather than bother with a UPS claim, I’ve decided to machine a new one. The only other shortcoming that I knew about is the paint; as you can see in the pics there a several scuffs and the paint has faded. Fortunately, the mount is in “Takahashi green”, a color much easier to match than the older “Takahashi gray”. These are for the most part “cosmetic” problems; the mount’s movements are still smooth and “tight”. Still, I have my work cut out for me – stay tuned!

#2 LLEEGE

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Posted 25 October 2009 - 10:19 PM

Good luck with the rebuild. Still a nice looking mount.

#3 TxStars

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Posted 26 October 2009 - 02:02 AM

You can contact Art at Takahashi USA and see if they have any spare parts, I know they have the paint.

#4 PJ Anway

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Posted 26 October 2009 - 07:00 AM

Thanks Luke. I'm hoping to use it with my FS78. A little overkill, but I like "steady" viewing!

Charles, I did contact Art about a drive controller and he has a ol' PD4 that he says would work. I'm also looking at a PD6 from another seller.

#5 TxStars

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Posted 26 October 2009 - 09:18 AM

Yep the PD-4/PD-5/PD-6 will all work with the EM-100.
The FC-76 will be great on that mount, when you get it all set up you will have a nice astrophoto rig.

#6 PJ Anway

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Posted 26 October 2009 - 07:36 PM

Charles,

Thanks for the info. I'll let you know what I end up with.

#7 PJ Anway

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Posted 26 October 2009 - 07:45 PM

Today I worked on the broken slow-motion shaft on the R.A. gear. I drilled out the old shaft from the spur gear, machined a new shaft and pressed it into the gear (pic #5 ). Here's a pic with the slow-motion knob back in place: pic #6. Also in the pic are the 3mm screws I was able to purchase at the local hardware to replace the missing ones on the R.A. gear cover.

#8 PJ Anway

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Posted 31 October 2009 - 01:25 PM

The project continues:

Over the last week, I was able to obtain two black Takahashi slow-motion knobs and the promised counterweight arrived from the seller. The knobs fit perfectly
(pic #7) and should help with navigating the skies without a motor drive. Also seen in the picture is my Losmandy G-9 tripod adapter plate. I found that the base of the Takahashi fits perfectly into the hole of the Losmandy plate. That will make things convenient. :grin:

The counterweight proved to be less promising. It is the 7 kg. (15.4 lbs.) weight and would be far too much weight for my FS78. I decided to machine a counterweight from a 8 lb. piece of brass I had (pic #8) . Here is a picture of the raw brass next to the finished product (pic #9). Notice that I needed to sleeve the piece of brass to fit the Takahashi counterweight shaft. Here is the final product alongside the Takahashi counterweight with the paint touched up (pic #10). Should be a better fit for my scope. Not sure if I will leave it in "natural" brass or paint it Takahashi "green"? Also seen in this picture is the counterweight shaft retainer nut that I machined for the shaft end.

With all the needed parts obtained or made, next in the project comes disassembly for greasing and painting.

#9 LLEEGE

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Posted 31 October 2009 - 10:15 PM

Looking good!

#10 PJ Anway

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Posted 02 November 2009 - 06:22 PM

Thanks Luke!

#11 PJ Anway

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Posted 02 November 2009 - 06:25 PM

Now I'm committed - ( pic #11 ) !!

#12 Charlie Hein

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Posted 02 November 2009 - 07:12 PM

I'd say so!

#13 TxStars

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Posted 04 November 2009 - 11:13 AM

Yep you have the majority of it apart.
Are you going to use the new color or the old when repainting it?
I have been thinking of powder coating one of my Tak mounts.

#14 PJ Anway

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Posted 04 November 2009 - 02:49 PM

I plan on using the new color, it's closer to the original paint on this mount. This is the only EM-100 I've seen in this color, all the other ones I've seen have been the darker gray color. I've started to mask the decals/labels. They are in surprisingly good shape and I believe if I tried to remove them, I might cause some damage. I would love to powder coat the mount, but don't have the means/talent to do it myself.

#15 PJ Anway

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Posted 04 November 2009 - 07:52 PM

I'd say so!


Charlie,

I took notes and pics during disassembly, so it should go back together relatively easily.

#16 Charlie Hein

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Posted 04 November 2009 - 10:29 PM

I'd say so!


Charlie,

I took notes and pics during disassembly, so it should go back together relatively easily.


I have great faith in your abilities in this regard. That said, when you break it all down (pardon the pun), that really is a whole bunch of expensive Takahashi parts all loose (as in not assembled) on a table. That's more than enough all by itself to give most stout hearted men a serious case of indigestion.

#17 PJ Anway

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Posted 05 November 2009 - 09:13 AM

Charlie,

I know what you mean; some knots in the stomach for sure.

#18 PJ Anway

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Posted 05 November 2009 - 09:14 AM

I finished painting ( pic #12 ) and will give the parts a few days to dry properly. Masking went well, coming off with no damage. I know from experience that this is not always the case (once I masked a label on a scope, only to have it come off with the masking tape). :crazy:

#19 LLEEGE

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Posted 05 November 2009 - 09:57 AM

Did you paint the brass CW? I like the brass look. Of course, it's your mount. :)

#20 PJ Anway

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Posted 05 November 2009 - 11:11 AM

Luke,

No, I'm still indecisive there. I will wait until I assembly everything and take a look, but I am leaning toward your preference.

#21 Ed Kessler

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Posted 05 November 2009 - 10:59 PM

One look at those bearings gives me a pretty big "hint" as to why my TAK EM-11 tracks better and more smoothly than any other EQ mount I've owned!!

Looks like the project is going well, PJ!!

Clear Skies,

#22 PJ Anway

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Posted 06 November 2009 - 07:44 AM

Thanks Ed. I noticed the bearings also, six total with four on the R.A. axis alone!

#23 PJ Anway

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Posted 07 November 2009 - 04:21 PM

Drying went well and I felt confident enough to go ahead and assemble the mount today. Here it is - back together! (pic #13). Re-greasing really helped, making its operation even smoother and I thoroughly recommend it.

Next I placed it upon my Davis & Sanford Astro 600 tripod (this is the tripod Astro-Physics sells as the SDS400 for their 400 mount). Here are a couple of pics with my FS78 in the "saddle": (pic #14), (pic #15). The shade of green is not a perfect match to the scope and clamp color, but I'm pleased with how close it came. Not bad looking for a 19 year-old mount, eh?

After I took the pics and was looking them over, I noticed the latitude adjustment screw looked a bit bare. On the previous EM-100 I owned, there was a knob on this screw (pic #2). I don't know if Takahashi left it out when manufacturing the late EM-100's or it's just another missing part. Anyway, I decided to go ahead and machine a knob, pressing it on the screw (pic #16). There - I think its complete!!

Let me know what you think. Any suggestions? Should I paint the counterweight to match or leave it as is? All thoughts appreciated.

#24 LLEEGE

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Posted 07 November 2009 - 07:49 PM

Looks fantastic! Great job! :waytogo:
I'd leave the CW as it is. Looks classy. :jawdrop:

#25 Ed Kessler

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Posted 07 November 2009 - 09:35 PM

Looks fantastic! Great job! :waytogo:
I'd leave the CW as it is. Looks classy. :jawdrop:


It has been interesting following this thread. You've done a beautiful job, PJ. I've often wished for these sorts of machining capabilities.

I vote to leave the counterweight as is.






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