Shaft and Linear Bearing Coaxial Mechanism

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Oplo
Posts: 6
Joined: Sun May 17, 2020 5:36 pm

Shaft and Linear Bearing Coaxial Mechanism

#1 Postby Oplo » Wed May 20, 2020 4:53 pm

*Edited - new images and videos*

Hi Forum,
I have uploaded a series of short videos explaining how the Oplo coaxial mechanism works but more importantly, what it provides the shooter in terms of rigidity and accuracy. Video 07 demonstrates this design aspect.
Both the joystick and coarse elevation mechanism were engineered from shooter requirements – especially the older shooter – and were not conjured up simply to re-invent the wheel.
The rendered images are for a 3D visualisation and are now very close to how the actual product will look in terms of colouring/styling for both the F6 and F7-Ti.

RENDERS 23_1.JPG
RENDER 14.JPG
RENDER 22_Side view.JPG
RENDER 20_ head-on.JPG
RENDER 21_rear view.JPG



After testing many bearing types I decided upon PTFE Lined Ceramic Bushes as they offered superior qualities. Recirculating ball were very good but they were noisy and they will gradually destroy the case hardened shafts by wearing in grooves leading to play in the mechanism. IGUS Drylin were fantastic however, once press fit into the float their static friction increased dramatically. PTFE Lined Ceramic Bushes have other qualities such as self lubrication and the ability to absorb foreign particles (videos at bottom).
Please note that this bearing test frame is using a solid steel joystick and handle – it weighs a lot and probably simulates a 30-40kg rifle. Actual product will be aluminium alloy.
In time I will make a series of videos on how the coarse mechanism works and the reasoning behind its development.
Feel free to comment or ask any question pertaining to the engineering and design (no sales or availability questions please).
PS. Please note that my ozfclass username has changed to reflect the brand Oplo.

Introduction to Linear Bearing Coaxial Mechanism
https://www.youtube.com/watch?v=A0bBydO_EGI
Freedom of Motion
https://www.youtube.com/watch?v=Ic7bLX6k0q0
No More Rocking of the Head
https://www.youtube.com/watch?v=rDdX2dflyxg

Videos on bearing choice
https://www.youtube.com/watch?v=aD224gX39G0
https://www.youtube.com/watch?v=V18paQ7HUCQ
You do not have the required permissions to view the files attached to this post.
Last edited by Oplo on Fri May 22, 2020 5:44 pm, edited 4 times in total.

Wal86
Posts: 274
Joined: Sun Nov 20, 2016 5:10 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#2 Postby Wal86 » Wed May 20, 2020 5:57 pm

Oplo,

Just looking at your photos, looks like the F6 rest at its lowest point would be still quite high?
May be an issue...

Just a thought,

Ratgun
Posts: 15
Joined: Wed Feb 22, 2017 8:21 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#3 Postby Ratgun » Wed May 20, 2020 7:42 pm

Just watched your videos looks good, what holds the weight of the rifle when and if you let go of joystick depending on shooting preference

Oplo
Posts: 6
Joined: Sun May 17, 2020 5:36 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#4 Postby Oplo » Wed May 20, 2020 7:47 pm

Hi Wal86
Yeah, that bag on top isn't exactly convincing, is it.
With the joystick mechanism in a central position of 7.5mm (15mm vertical range is pretty big), coarse mechanism fully lowered, feet fully screwed in, rifle on level ground and with a 40mm bag (top surface of vertical float to under surface of stock) the measurement is 195mm from ground to stock.

On level ground, a McMillian F Class stock with a bigfoot rest (without any rear bag support) requires 210mm from ground to stock. If using a rear bag support of say 25mm, then you would require an elevation of 40mm to the front rest.

There's 15mm of spacers in the column bearing units, 20mm of material which can come off the vertical float and column carriages and 5mm off the feet pads if absolutely required. That's another 40mm to play with if I have to - I want to preserve these but if they need to go then so be it.

So, -15mm just with a rear bag, -40mm with a rear support under the rear bag, and -80mm with a full solution.

Oplo
Posts: 6
Joined: Sun May 17, 2020 5:36 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#5 Postby Oplo » Wed May 20, 2020 8:02 pm

Hi Ratgun,
Well, firstly, I need to point out that-that steel joystick weighs a ton.
We will be testing the rest with a counterweight on the front of the joystick (note the hex bolt in the front spherical bearing in the video). If this in any way detracts from the bearing smoothness or creates too much inertia in the movement then we will fall-back to spring-loading the vertical float off the horizontal float. Either is a piece of cake to modify into the prototype.

John T
Posts: 205
Joined: Sat Jan 07, 2006 5:42 pm
Location: Brisbane

Re: Shaft and Linear Bearing Coaxial Mechanism

#6 Postby John T » Thu May 21, 2020 9:35 am

Hello Oplo.

What is the all-up weight of your rest?

Regards,
John T.

Oplo
Posts: 6
Joined: Sun May 17, 2020 5:36 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#7 Postby Oplo » Thu May 21, 2020 1:15 pm

Hi John,
We have several versions of the base (casts with various pockets for lightening) which will provide a final product weight of between 13kg and 17kg.
The F7-Ti will be lighter and have a final product weight of between 10kg and 14kg. This is due to horizontal and vertical floats, column carriages and joystick rod being machined from Titanium.
We will decide the version of cast once we have tested the prototype - we'll start heavy and machine it down progressively.
We can reduce a further 1kg from both versions by switching to Aluminium Alloy feet.

willow
Posts: 320
Joined: Sat Aug 15, 2015 9:51 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#8 Postby willow » Sat May 23, 2020 6:37 pm

Interesting to see how this product evolves from test phase to production.

John T
Posts: 205
Joined: Sat Jan 07, 2006 5:42 pm
Location: Brisbane

Re: Shaft and Linear Bearing Coaxial Mechanism

#9 Postby John T » Sat May 23, 2020 7:56 pm

Hello.

Please do not take anything I say as discouragement. But, your rests are heavier than our F Open rifles. I think many of us would struggle with them on the mound. They would be prohibitive for international travel. BR would seem to be your target.

Best wishes,
John T.

Oplo
Posts: 6
Joined: Sun May 17, 2020 5:36 pm

Re: Shaft and Linear Bearing Coaxial Mechanism

#10 Postby Oplo » Sat May 23, 2020 8:36 pm

Hi John,
Not taken as discouraging at all mate.
The F7-Ti can be pulled down to around 10kg if required so if a national/international shooter wants that option then great. In my mind the F6 is for the club shooter who typically travels by vehicle and where air travel isn't really on the agenda.
A few mates were once professional cyclists, they traveled with 20kg bicycle travel boxes and 30kg of gear/clothes all over the planet, 11mths of the year. I think that's the cost of being at the top end.
At the end of the day I'm focused on those shooters out there who want something different, something you don't see every day, the 5%-ers.
Cheers
M


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