DiscMounts DM-6 Alt-Az mount.. first light

[snaggs]

Well, whilst I wait for my Gran Turismo to arrive, I have been enjoying another fine APO, namely a Takahashi FS-60CB. So how did it go?

The DM-6 has changed my life... why did I persevere with GEM mounts for all those years? and my worries about guiding at high power were unfounded.

Last night I spent much of the evening gazing at Jupiter at 142x (Extender-Q and Zeiss 4mm), saw the 4 moons, banding on the planet etc. Also saw the Eta Carina nebula, M5, Omega Centauri and the jewel box. Just gorgeous! Star resolve to pinpoints like nothing I have seen. The FS-60 has more detail, resolution, everything than the 4" Nextstar I owned (and tracks better by hand with the DM-6!), isn't as good on dim fuzzies as the 6" chinese newtonian I had, but once again, better on planets and much nicer on star fields. Only the 8" Meade LX-90 has given me more detailed views, but I still think I prefer the 60mm Tak and its rendition of the Jewel Box trumps the 8".

Tracking was no problem at all, even at 284x when I stuck the Zeiss 2x barlow in just for kicks (at this resolution the baby TAK did experience some image degradation). I'm glad I ordered the optional handle, it is very convenient to use. Did I mention that the DM-6 has no back lash?

The Sky Commander performs as advertised, and once again I was wondering why I had put up with batteries, cords and whirring motors. The push-to is much faster.

In hind sight, I wish I had just bought a nice Tak or Vixen apo to start with all those years ago on a Alt-Az mount. I would have saved myself alot of chopping and changing.

PS. I have compared the DM-6 to the Tak Teegal, and it is clearly more stable... still I'll put up with a 2s dampening time and be able to take my scope into the country with me on my motorbike. They are different beasts.. and I'd have either over any GEM, never never again..

Daniel.
Perth, Australia

PS. Other photo's of the scope are in the Takahashi FS-60CB first light thread, or in my post on the DiscMount discussion group;

http://tech.groups.yahoo.com/group/discmounts/messages

[dannat]

great looking mount & scope -280x at 60mm of aperture is a bit of a stretch though.
Is it the zeiss abbe's that you have?

[Miaplacidus]

Well, I'm not sure how to describe the shade of green I've turned, but you get the idea. Congratulations. Where did you source the Discmount???

Cheers,

Brian.

[snaggs]

Yes it is a stretch. 142x is v.sharp though, and does look a like the photo's on the Tasco boxes :)

Also affirmative to the Zeiss Ortho's, and they make a difference, even with 60mm of aperture.

Daniel.

[snaggs]

Direct from the maker. The whole mount has been CNC machined from solid steel. Considering the mount (not the legs) can take 7" APO, its a bargain.

http://www.discmounts.com/

They also have a DM-4, I don't know why anybody would by an iOptron when you can buy a mount like this can be had for only $800 US.

The quality difference is like comparing Tasco to Astro-physics.

Daniel.

[JethroB76]

Looks great! I see one of these in my future

[snaggs]

If your interest in Alt-Az, also check out the Tak teegul alt-az mount I have here;

http://www.iceinspace.com.au/forum/showthread.php?t=48241

It was TG-SK for FS-60 and cost me $750 delivered from Claudio and included rings for the FS-60. You can get versions without rings.

Daniel.

[wavelandscott]

The DM6 is the next bit of gear on my list...except i will substitute in an Argo Navis for the Sky Commander.

I checked them out at NEAF and they sure are finely made!

Congratulations and enjoy!

[cohiba]

Hi Snaggs
What a great mount I have not seen one before I live in Perth and wouldnt mind getting a look at it in the flesh. I have a fixed observatory but am looking for a portable setup I can take out into the bush how do you find the sky comamder ?

[snaggs]

Sky Commander is very simple and easy to use. Its packed full of more catalogs than I poke a stick at. You can also load in your own lists via Excel Spreadsheets.

Where in WA are you? Next time there is a clear evening on the weekend I want to get up to Orange Grove.

Daniel.

[cohiba]

Hi Snaggs
I live in the Vines so if you organise somthing give me a shout and I will come have a look see

[Wavytone]

If you're looking at a DM6 then maybe you should also investigate the Half-Hitch MkIII as well.

Having had an altaz mount for a year, I'm thinking about upgrading to the Half Hitch rather than the DM6 as I like the really free motion of the HH, provided the scope is balanced.

[snaggs]

Looks very nice, not sure how it compared to a DM-6 which can handle 6"-7" APO's. Nice none the less, I'd love to compare both side by side.

Either way, GEM's are looking very sad indeed.

Daniel.

[Wavytone]

Snaggs, the real difference will concern how easily you can make small movements at high magnification.

The altaz mount I have currently uses preloaded bearings and teflon sleeves to provide drag with seemingly little or no stiction. In practice this is ok up to about 120X but at 200X its a nighmare for example to locate and track a planet; once lost getting it back in the field means switching eyepieces.

Looking at the DM6 it appears to rely on pre-loaded bearings + teflon between the large disks - and I suspect it suffers from exactly the same issue.

OTOH the HH mount uses free-running bearings and rollers to control its motion, with clutches. If the maker has really managed to make this work as well as it should, the HH should be vastly superior at high magnification. The downside is the scope will have to be well balanced, so it will be desirable to use a set of eyepieces that are all roughly the same weight. I've asked how these work on the CloudyNights forum and all the owners that replied were very happy with them and confirmed they can use high powers on 8" SCT's on the HH mkIII.

As you say it craps all over GEM's.

[snaggs]

Hey, you might suspect it, and I was worried about that too, but you'd be wrong!

The huge discs make it very consistent, I have tracked at 280x no problem. I have a new toy that arrived today, so soon I'll be able to tell you about higher powers..

Daniel.

[DiscMounts, Inc]

Hi!



I’m Tom Peters the designer and manufacture of DiscMounts products. I have been in the hobby for over 50 years. Some years ago, I bought a TV NP-101 to use as a terrestrial and astronomical telescope when camping. The three things I demand in a mount, rigidity, smoothness, and being able to change eyepieces without the telescope moving, wasn’t available, so I designed and built my own. After prods from my friends and family to produce a similar mount, I started DiscMounts, Inc. Even though the rewards from manufacturing a very high quality mount has been great, the friends I have made all over the world has been even better. DiscMounts, Inc. has been nothing but fun!

Just some general comments about the DM-4 & DM-6!

The DM-4 and DM-6 are close coupled designs, with no struts or arms to vibrate. When vibration is considered the axis are just very big and short shafts (6” for the DM-6 and 4” for the DM-4). The design also allows the two axis to be very orthogonal, which DSC’s require to be accurate and consistent.


The friction discs are not Teflon! Teflon is soft, cold flows, has stiction problems, and wears out fairly quickly. The material I use (selected after years of experimenting. The first friction mount I designed and still use is 40 years old), is very tough (must be machined), has no stiction, and will last the life of the mount.

The DM-4 and DM-6 have two moving parts, and will last many years, with care, a lifetime. There is no maintenance! All our products are Type-3 hard anodized, which is very scratch resistant. Type-3 is not the same as the anodizing most manufactures use. There is no paint! There has been only one design change to the DM-6, the addition of two spring washers. None to the DM-4! The first DM-6 and DM-4 look and operate the same as what I’m shipping now. The design is very simple, and works.

The DM-4 is a down sized version of the DM-6, designed for the 4” and under grab & go scopes. It can handle a light 130 very well. It weighs, 6 pounds with saddle and is not much bigger than your hand.

The friction system is made adjustable so it can be tailored to the accessories being used, and can be changed easily when accessories change. Most owners find the adjustments they like and leave it there. I advertise 0-2.5 pounds for the DM-6 and 0-1.5 pounds for the DM-4 without changing the balance or adjustments. Some customers are going beyond these limits.

When tracking by hand the friction, unlike bearing mounts, actually helps. There is no over shooting the object then having to compensate. The mounts are so smooth and ridged, tracking is easy.

The advantage of the Sky commander over other DSC’s for the DM-6 &DM-4 is it’s small size, long history (15 years), easy use and Vic the Manufacture is a friend and local to me. That said, Gary (Argo Navis) and I have worked out cables for the Argo. The Encoders and cables must be sent to me and for a nominal fee I will install them. We have done many! Both DSC's are great!

Thanks for letting me shoot my mouth off! Hope I haven't come across to strong. Please visit out website at www.discmounts.com (http://www.discmounts.com/) If you like to see pictures of telescopes, be sure to visit the “Galleries”!

Tom

[Dennis]

Hi Tom

Welcome to Ice In Space and thanks for the details on the DM-4 and DM-6, they sure look sweet and I can see one or other of these in my future! Daniel (snaggs) sure makes these sound like a must have mount!

Cheers

Dennis

[snaggs]

I'll get Cohiba to post his thoughts once he has had a play!

Daniel.

[cohiba]

Snaggs
Look forward to an invitation

[casstony]

Thought I'd add my 2 cents to this old thread since I recently purchased a used DM6 from Astromart. I can track fairly easily at low to mid powers and there is no tendency to lose the object (the mount doesn't run away from you at all). The altitude axis is very easy to control while the azimuth is a little less so - just a touch jerky for minute adjustments, though I may not have the tension set perfectly yet. I may couterbalance the azimuth axis, particularly if I end up putting a C11 on it, which should make it perfect. I easily tracked a couple of satellites across the sky in a low power eyepiece - I use a laser pointer as a finder so it's easy to point the scope ahead of the satellite and catch it in the eyepiece. If you don't have the cash for these expensive mounts don't worry - a dob does a similar job for a lot less money - just depends on your preferences.

It'll be interesting to see how the DM6 compares to the new T-Rex mount when it's available.

[Steffen]

Tom, do you reckon the DM-4 is sufficient for a 6" Mak (Intes MK-67)?

Cheers
Steffen.

[casstony]

Steffen, you might want to ask your question on the Discmounts yahoo group or directly to Tom; he may not monitor this thread. The stated load limit for the DM-4 is 18 pounds.

[wavelandscott]

I agree with this advice, Tom was very responsive to me when I had questions...

[Steffen]

Thanks, I had a look around the Discmounts yahoo group, it turns out this sort of question gets asked over and over… :)

The consensus seems to be that the DM-4 will carry a C8 without problems, so a 6" Mak should be fine.

Cheers
Steffen.

[Waxing_Gibbous]

Grrrrrr. Rowwwwr! Check back in a week or so! :)

[Steffen]

Mmmm, drool… I sure will. The T-Rex was the mount I originally looked at, which brought me to the DM. There isn't a lot of people that have used both apparently, so I'm eager to listen to some first hand insight.

Cheers
Steffen

[wavelandscott]

In ignorance there is bliss with respect to the T-rex...I get my DM-6 in a few weeks...I only want to hear about a comparison between the two if the DM comes out on top.

[DiscMounts, Inc]

Sorry, but I seldom get the time to visit all the forums. I always respond to my emails, if there’s something on a forum I should answer and don’t, please email.

Casstony mentioned he had slight stiction on his DM-6 az axis. There should not be any stiction on either axis. Slight stiction can be caused by the friction adjusting nut being to lose. The mount is used, so maybe there’s a problem, it’s hard to hurt one, but you never know. Casstony if you haven’t got it worked out, email me off-line, maybe I can get it back on track for you.


The C-8 is a good match for the DM-4. Steffen, I use a TEC-6 with mine, it work very well. Since I don't think manufactures should tout there products on forums, it's best to email me.


Scott, your DM-6 is on my bench behind me. It looks so good maybe I should keep it for my self. Don’t you think!! I’ll see you at NEAF and will give you the grand tour!

Tom

[gb_astro]

There is a long thread on Cloudy Nights about the T-Rex with some good photos and a comparison to the DM6.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3619136/page/0/view/collapsed/sb/5/o/all/fpart/2/vc/1

gb.

[wavelandscott]

Scott, your DM-6 is on my bench behind me. It looks so good maybe I should keep it for my self. Don’t you think!! I’ll see you at NEAF and will give you the grand tour!

Tom[/QUOTE]

:cool::love: I look forward to it!

[casstony]

Hi Tom, I haven't used the mount since I got the Sky Commander sorted out - it's waiting for a new ota which I should have in the next few weeks. The striction is only with micro-movements in the Az axis but I'm very happy with the mount overall; if there seems anything abnormal after I've played with the new ota I'll contact you in future.

I've made a balance plate to experiment with too - curious to see whether it's useful or not when using a 30 pound cassegrain. The inside nut is welded in place so the shaft can be screwed in without having to remove the plate. The welding shop had 6mm flat bar the correct width so they just had to make two cuts and they tack welded the nut on for me, all for the princely sum of $2.

[DiscMounts, Inc]

Actually the DM-6 was designed to have a counterbalance if needed, this is why the back plate is so thick. I stock a few, with an aluminum plate and 1.25" stanless steel shaft (there's pictures in the DiscMounts forum picture section). Originally the top plate was designed to slide off and the counterbalance dropped into the rear groves, rather than unscrewing the the shaft. A few customers wanted to beable to mount the scope on either side of the mount. To do this I had to change the Sky Commander top plate, which was originally designed to easily remove the cable, to a plate with a universal cable pass-through. Unfortunately the with the new universal SC plate it's difficult to remove the cable to allow the counterbalance assembly to drop in. I don't advertise the counterbalance, because I don't want customers thinking it's alwayse necessary. It's only needed for the heavier scopes.

The original DiscMount (?) is a 40 year old equatorial with 8.5 inch disc and 9" gears on both axis. Equatorial mounts require a counterbalance. When I design I try to allow for the future, I wanted to do a tracking platform, but never had the time.

If you stay inside the specs, it's very difficult to hurt a DM-6 or DM-4 (they can be cosmetically damaged, but even that is hard). I like simple designs because there's less to go wrong, especially at night. I designed the the Discmounts to last a lifetime with little or no maintenance. The friction disc is NOT teflon and should last longer than you or me. There's only two moving parts so there's not much to wear-out. If you still have problems with your Az axis email and I'll help you figure it out. I have tracked at 700 power, and I just received a call from a customer that was tracking at 500 power. It's not what you would want to do all the time put it's possible, but both axis have to be smooth to do it.

Tom

[casstony]

I wasn't aware that you make a balance plate Tom; I found the pictures you referred to. I prefer being able to screw the shaft into the plate since that allows the plate to be left in permanently - no mucking around with the top plate and cables each time the mount is moved. Your alloy plate and the thicker shaft are nicer than mine though; I've pinched the shaft off my EQ5/Skyview Pro mount.

Cheers,
Tony

[DiscMounts, Inc]

Tony,
Your counter weight looks very nice and serves your purpose. Mine are expensive. I only keep a few in stock and making low quantities is expensive. The Hard coat is 10 times the volume price, and that's if it is plated at the same time as the mounts.

My big mount is portable, but the counter weight is 80 pounds. I needed a way to mount an dismount such a heavy best, as an assembly. The DM-6 has a similar design. The DM-4 was designed to allow the 2" hi res. encoders to be used, so space was at a premium, and I couldn't carry the sliding cover idea through to it. The DiscMounts are designed as a box for two reasons: I can make very accurate right angles, which means the mount is very orthogonal, and it's easy to make "stuff" to mount on a box such as the counter weight.

Hope I'm not violating my own rule of not selling on a forum. I always liked knowing why an engineer went in one direction over another.

Tom

[casstony]

No problem at all Tom; it's better to err on the side of providing more information.