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New Crossbow EQT-200 Equatorial Platform Arrived.

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#1 Project Galileo

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Posted 15 March 2013 - 10:31 AM

I love reading threads about people's new gear. Every time I get new stuff, like this eq platform, I like to share too. So here is a thread about my experience.

For those who aren't familiar with EQ platforms they are placed on the ground, aligned to polar north, and a dobsonian telescope is placed on them. The platform is cocked or reset then turned on. A stepper motor, moving the same speed as the Earth's rotation, then cancels the earth's rotation. This has the effect of keeping a viewed object in the center of the eyepiece without touching the telescope. Without an eq platform the astronomer would have to keep nudging the telescope to follow the object as the Earth rotates. Eq platforms make viewing easier and allow for using higher magnifications since you don't have to manually track an object speeding trough the field of view while zoomed in.

I looked into building a platform as many astronomers do. After all was said and done I felt having a pro do it suited my needs best. Looking around I found three platforms I liked. The Terry O aluminum platform was at the top of my list but also at the top of the price list. Atomic Platforms are still made and are also nice. However, they were a tad undersized for my Lightbridge 16's weight. They are also only sold on Cloudy Nights on a first come first serve basis and come for sale intermittently. The final contender was the Blandin Technical Solutions "Crossbow" eq platform. They had two models of all aluminum platforms priced right.

At the end of November 2012 I ordered a "Crossbow" EQT-200 equatorial platform from Greggs Blandin of Blandin Technical Solutions, 42B Union Way, Vacaville, CA 95687. He can be reached by email at Greggsblandin@earthlink.net. Gregg offers two sized single axis plaforms, an EQT-120 and EQT-200, given their names from their load limits. Greggs makes them in batches so I was on the list for his next batch.

I first contacted Greggs and talked with him extensively about his products. He is an excellent guy to chat with and very knowledgeable. We talked about the genesis of his platforms and their function. He emailed me a flyer and an order form. The order form asked basic information like the weight of your telescope, the diameter of the teflon pads needed, center bolt size, thickness of rocker box, observing latitude, etc. After filling it out and sending Greggs half of the money he went to work.

I selected the Crossbow EQT-200 platform for many reasons. With a load capacity of 200 lbs. it would easily handle my LB16 and also handle any new larger telescope. Greggs said others have placed up to 28" telescopes on these platforms. For $900 it was a steal. A comparable Terry O would go for $2000-$3000. I also like the minimalist all black look of the Crossbow. It matched my telescope well.

Recently Greggs notified me it was completed and he had tested it extensively. It was ready to ship. I sent him the balance and it arrived in the mail this week. The box was well padded on the inside with foam lining. Each part was bubble wrapped extensively and squeezed into the padded box. Greggs had also emailed me assembly instructions. To save on shipping he partially dismantles each platform so there is some assembly required. Everything was perfect after unwrapping. Finish of each piece was impeccable and professional.

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#2 Project Galileo

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Posted 15 March 2013 - 10:35 AM

First was to build the lower bearing and drive assembly center support. Two arms swiveled out on each side easily. There are two wires that need to be attached. These go to the stepper motor. I found out that these wires can be switched to switch the direction of the motor. This allows the platform to be used in the southern hemisphere too. After I had it set up and the platform was tracking in the opposite direction I thought I emailed Greggs. He replied immediately letting me know about the wires. The arms are secured with screws on top and bottom.

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#3 Project Galileo

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Posted 15 March 2013 - 10:44 AM

The polar axis support assembly has an on off switch for the platform. A plastic connector and four bolts went together perfectly and secured the axis support soundly. Fit and finish are above average for this platform.

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#4 Project Galileo

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Posted 15 March 2013 - 10:50 AM

The plastic end cap at this end of the plaform comes off revealing the battery pack. It came from the maker with batteries in place. Four AA alkaline batteries will run this unit for approximately 40 hours.

At the other end of the lower bearing and drive assembly center support the cap comes off too. This reveals a small circuit board. This board regulates the voltage giving just the right amount of power to the motor. You can use a 9v battery, four AA, or two D cells. Each will be regulated to the correct amount going to the motor. Versatile.

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#5 Project Galileo

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Posted 15 March 2013 - 10:53 AM

The bottom of the platform is equipped with three leveling feet.

Completed lower part.

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#6 Project Galileo

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Posted 15 March 2013 - 11:08 AM

The platform uses a stepper motor with metal gears. It makes a tad bit more sound than other motors however it is nearly bullet proof. Greggs prefers these for their durability.

Proper drive friction is essential to platform performance. The ideal amount of drive friction is slightly more friction than the minimum needed to drive the platform through its entire range. Excessive drive friction will make resetting the platform difficult and put stress on the drive gears. The drive friction is increased or decreased by raising or lowering the drive friction lever on the drive side arm. Raising the drive friction lever increases the drive friction by lowering the black drive side bearing. This allows the weight of the telescope to rest on the orange drive wheel and be shared by the black bearing. This gives the orange drive wheel traction to move the telescope without having to bear the entire weight thereby increasing drive effort and wear. Lowering the drive friction lever decreases the drive friction, by raising the black free wheeling drive side bearing shifting weight off of the orange drive wheel completely. To reset the platform, switch the platform electrical switch to the “off” position. Lower the friction lever as shown. While holding the lower assembly in place, push the platform top away from that side until it reaches the stop. Raise the lever as shown, then switch the platform electrical switch to the “on” position.

I was told by Greggs that this is the first batch of platforms with this new friction lever. It really makes resetting a breeze. When the lever is released resetting takes minimal effort.

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#7 Project Galileo

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Posted 15 March 2013 - 11:11 AM

The upper arm assembly was the next thing to assemble. Two arms pop out. Two other support arms are then attached to the main body. The ends of the arms are held in place by a small bolt on each side. Then the center is tightened.

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#8 Project Galileo

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Posted 15 March 2013 - 11:13 AM

The upper arm is then attached to the polar axis support assembly. Ready to roll.

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#9 Project Galileo

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Posted 15 March 2013 - 11:15 AM

There is a center retaining bolt with a knob on it that is used to hold the upper arm to the lower bearing and drive assembly center support during transport. The retaining bolt fits into a threaded hole on the lower bearing and drive assembly center support. When tightened both the top and bottom are held together when you lift or move it. This prevents lifting the upper part up alone and bending the polar axis support.

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#10 Project Galileo

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Posted 15 March 2013 - 11:19 AM

Here it is completed. It took me 15 minutes to assemble and take pictures. Pretty straight forward. It weighs just over 19 lbs. and is about 5 inches tall. The teflon pad placement was chosen based on my current telescope's size. Switching the location of the pads is easy by drilling three new holes. This makes the mount infinitely adaptable to any sized scope up or down. When you mount a telescope a long bolt is put through the base's center pivot and then screws into the platform via threads. Very easy and fast.

This platform was custom made for my latitude. However, if I change locations the feet can be raised or shimmed to adapt to the new viewing location on the globe. By lifting the north or south end 1/2" it will adapt to one degree of latitude. Very flexible.

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#11 Project Galileo

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Posted 15 March 2013 - 11:24 AM

Here I have put the telescope's rocker box/base onto the equatorial platform. This is not a stock LB16 base. I built it from birch plywood and laminated it in flat black. The new base completely disassembles with the knobs and breaks down for travel. It is way stronger and lighter than the stock press board mess it came with too. The eq platform takes the place of the ground board which is not used.

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#12 Project Galileo

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Posted 15 March 2013 - 11:28 AM

Here it is "cocked" or reset and ready for just over an hour of tracking before needing to be reset.

There have been cloudy nights since it came so it still awaits first light. However, setting it up and running it indoors lets me know it works perfectly.

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#13 btb

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Posted 15 March 2013 - 01:03 PM

Nice looking rig. You did a fine job explaining the assembly. :waytogo:

#14 rockethead26

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Posted 15 March 2013 - 01:13 PM

Congrats on the new platform. After you get a chance to use it outside, I'm curious to know whether or not the "tail" that sticks out is a trip hazard in the dark.

#15 Chucky

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Posted 15 March 2013 - 02:15 PM

<< However, setting it up and running it indoors lets me know it works perfectly. >>

.....perfectly indoors doesn't necessarily equate to perfectly outdoors under the stars in the heat of battle. I bet it will work fine outside, but one never fully knows until real world application.

#16 Project Galileo

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Posted 15 March 2013 - 03:24 PM

After this platform was finished Gregg Blandin, the maker, ran it through complete testing under the stars with a telescope installed. When I talked with Gregg when it was completed he told me that it tracked effortlessly and accurately as he described the testing process. This is a custom manufacturing process with low numbers. Quality control is very high. I have every confidence that this platform works perfectly even in the heat of battle.

#17 demiles

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Posted 15 March 2013 - 05:18 PM

I've been using one of Gregg's platforms for the last 10 months and it truly a great product. You won't be disappointed.

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#18 demiles

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Posted 15 March 2013 - 05:34 PM

I have kicked that end just once while viewing straight up at zenith.

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#19 ZuoZhao

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Posted 16 March 2013 - 08:29 AM

it can use for plantes imaging ? I means use F20 or more.

#20 demiles

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Posted 16 March 2013 - 09:51 AM

I suppose you could, I'm able to view planets at f15 on a regular basis. I'm not an imager so there could issues I'm not aware of.

#21 demiles

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Posted 16 March 2013 - 12:00 PM

I forgot to mention that the biggest advantage to Gregg's platform is stability. It's every bit as if not more so than the original ground board. Most other platforms are a compromise especially on a grass field.

#22 Mantis707

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Posted 16 March 2013 - 03:32 PM

Very cool! thank you so much for taking the effort to do such a thorough job / write up..... This is immediately on my wish list when I get a light bucket.....

#23 bilgebay

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Posted 16 March 2013 - 04:15 PM

Congratulations on the new mount!

This is a great write up! Thanks.

#24 G Blandin

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Posted 16 March 2013 - 05:47 PM

Thanks for taking the time to do such a thorough and detailed write up! I'm really glad people like the product. I've put a lot of effort into designing and building these so having happy customers makes it really worth it.

#25 Aperturefever

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Posted 17 March 2013 - 03:45 AM

Hi Doc,
I really must stop looking at your posts ... every time I do it ends up costing me money! :grin: Excellent write-up - this is something I've been looking into for a while to help with my sketching. I'm looking forward to hearing a review of its performance. In the meantime, I'll start swinging the hammer at the piggy bank!






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