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My friend and customer Ray designed a base for a Ham radio antenna that will eventually be mounted on top of a school, which is the highest point in the area. I machined all of the components for the antenna base. The antenna will be used for a Ham radio repeater station. The school didnt want him to drill holes through the membrane of the roof, so it has to rely on weight and a large base to keep it from tipping over in the wind. The first step was to face and cut the stock to length.1. Cutting Off Stock 1
2. Cutting Off Stock 2
The next step was to set it up on the Bridgeport to cut the slot. I removed the chuck from the lathe and clamped it to the Bridgeport. Then I used a center finder to find the center of the stock so that I could zero my digital read out.3. Finding Center
Next, I drilled the center hole undersize just to remove some stock. In hind sight I should have done this step while the base was still in the lathe. (It is easier to drill a hole with the 7-1/2 HP lathe as opposed to the 1 HP Bridgeport.4. Pilot Drilling Stock
5. Drilling Stock
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:The next step was to cut the slots. I used a 1 roughing end mill. The depth of cut per pass was .050 and the speed was 800 rpm. The roughing cutter is a six flute endmill. The finishing cutter is a four flute endmill.6. Roughing Cutter
7. Finishing Cutter
The last mill operation was to tap the four 5/16-18 UNC holes. I tap drilled the four holes deep enough to provide room for chips, so that I could use a spiral tipped endmill. I tapped ½ inch under the power of the Bridgeport then backed off to clear chips. I tapped the last ¼ inch by hand. I have some spiral fluted end mills, which would push three chip streams out of the hole, but the ones that I have arent designed for steel.8. Tapping four holes
The next step was to go back on the lathe to bore and counter bore the center hole. If I were smarter, I would have done this during the first lathe cutoff and facing operations.9. Boring Base
10. Counter Boring Hole
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:11. Chamfering Bores
And here is the base all done with lathe and mill operations:12. Base All Done
The next step was to drill and countersink the legs followed by chamfering the end of the leg. My 45° chamfering end mill has enough flutes that I can cut a 3/8 chamfer in steel in one pass very nice.13. Chamfering Leg 1
14. Chamfering Leg 2
I really like the M. A. Ford style of countersink because it cuts clean without chattering. They can also be used on a drill press, because they are self-centering.15. Countersinking legs
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:16. Legs Done
I drilled the scrap piece left over from the base. I figured the antenna mast could use some additional mass to keep it from tipping over in the wind.17. Drilling the scrap as a counterweight
The next step was the mast. I added a cap to the top to keep it from filling with water and possibly freezing or corroding. The other side had a collar to trap the mast in the base and to prevent it from rotating relative to the base. (The scrap tubing was just to show you how the pieces fit together.)18. Making caps for the mast
19. Three mast pieces in exploded view
20. Three mast pieces together
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:I welded the cap to the top and the collar piece to the other side.21. Cap welded to mast
22. Other end welded to mast and dressed
Next, I assembled the antenna mast components.23. Mass inserted into base
The collar on the other end of the shaft was .005 proud of the counter bore, so when the legs were bolted on, they would clamp the mast shaft to prevent it from rotating.24. Mast proud of base
25 Legs clamped to base
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:And here is the antenna mast base all done. The counter weight, which is not shown, would slide on the mass and rest on the base to add additional weight to the base.26. Antenna Base All Done
-DonSmith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:Nice write-up with lots of photos.Would they have allowed a flat base stuck down with roofing tar ?MillerMatic 252, HTP 221 w/cooler, Hypertherm PM45, Lincoln IdealArc 250 AC/DC"I'd like to believe as many true things and as few false things as possible"
Reply:
Originally Posted by frieed
Nice write-up with lots of photos.Would they have allowed a flat base stuck down with roofing tar ?
Reply:Beautiful piece of engineering, great machining and even better description and pictures of the process.And totally overkill for the task at hand! (in my humble opinion!
)How about some concrete filled buckets on top of those legs? That should add more than enough weight and stability to the base.Mikel
Reply:It does seem like there would be easier ways of accomplishing the “no damage roof mount” task. Could even include some welding.Really nice job though.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:I would have copied this design or even just bought one of these from Rohn. Depending on the application they are from $150-$500
Miller Multimatic 255
Reply:Depending on the antenna they are using and how it attaches to your base, you may need to solder a ground wire to your legs to act as ground radials. Would greatly improve the antenna performance.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:That is a thing of beauty! I like to think that this creation is shown to the students, along with the pics and descriptions of how it came to be.Almost seems like the young figure everything magically comes in a box after picking a picture on the internet. Have to find that one or two that get the "hands on" bug to continue the tradition of self fabrication and problem solving.Yeswelder MIG-205DS(3) Angle Grinders at the ReadyJust a hobbyist trying to improve
Reply:
Originally Posted by Louie1961
I would have copied this design or even just bought one of these from Rohn. Depending on the application they are from $150-$500
Reply:
Originally Posted by wb4rt
Depending on the antenna they are using and how it attaches to your base, you may need to solder a ground wire to your legs to act as ground radials. Would greatly improve the antenna performance.
Reply:
Originally Posted by Kevin_Essiambre
I use these all the time for cameras and wireless internet equipment. They work great but I feel for a ham radio antenna They might not be the best item.
Reply:
Originally Posted by Louie1961
Actually Rohn is famous for making profession and amateur radio towers. This is essentially designed for a ham radio antenna.
Reply:It's a fun hobbyMiller Multimatic 255
Reply:
Originally Posted by Mikel_24
How about some concrete filled buckets on top of those legs? That should add more than enough weight and stability to the base.Mikel
Reply:Looks great.... I'm wondering if guy wires would accomplish more than extra weight on that roof. Anyplace to attach them without getting in trouble?250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:
Originally Posted by Louie1961
Burt, its a 2 meter repeater they are setting up for. The antenna likely already includes the radials as part of the antenna.
Reply:
Originally Posted by Don52
Ray's comment on your suggestion:"I guess I would have considered it if I knew about it. Maybe I should have looked more."
Reply:
Originally Posted by Louie1961
Don, you should probably consider some diagonal supports from the legs to the center mast.
Reply:
Originally Posted by Louie1961
Burt, its a 2 meter repeater they are setting up for. The antenna likely already includes the radials as part of the antenna.
Reply:Something like this? https://www.ebay.com/itm/11180212758...id=10028262107
Originally Posted by farmersammm
Does that mean the antenna is two meters high? I guess it's a full wave antenna??? I don't know much about this kind of stuff.
Reply:Here is another vertical array.
Smith Oxyacetylene TorchMiller Dynasty 200DXLincoln SP-250 MIG WelderClausing/Coldchester 15" Lathe16" DuAll Saw15" Drill Press7" x 9" Swivel Head Horizontal Band Saw20 Ton Arbor Press BridgeportLincoln LE 31 MP & Lincoln 210 MP
Reply:
Originally Posted by farmersammm
Does that mean the antenna is two meters high? I guess it's a full wave antenna??? I don't know much about this kind of stuff.
Reply:
Originally Posted by farmersammm
Something like this? https://www.ebay.com/itm/11180212758...id=10028262107
Reply:Looks like a great job.Like milling most time on site I see welding.Dave
Originally Posted by Don52
My friend and customer Ray designed a base for a Ham radio antenna that will eventually be mounted on top of a school, which is the highest point in the area. I machined all of the components for the antenna base. The antenna will be used for a Ham radio repeater station. The school didnt want him to drill holes through the membrane of the roof, so it has to rely on weight and a large base to keep it from tipping over in the wind. The first step was to face and cut the stock to length.1. Cutting Off Stock 1Attachment 17273612. Cutting Off Stock 2Attachment 1727362The next step was to set it up on the Bridgeport to cut the slot. I removed the chuck from the lathe and clamped it to the Bridgeport. Then I used a center finder to find the center of the stock so that I could zero my digital read out.3. Finding CenterAttachment 1727363 Next, I drilled the center hole undersize just to remove some stock. In hind sight I should have done this step while the base was still in the lathe. (It is easier to drill a hole with the 7-1/2 HP lathe as opposed to the 1 HP Bridgeport.4. Pilot Drilling StockAttachment 17273645. Drilling StockAttachment 1727365
Reply:Ray will use some type of an array antenna like the one shown below.
Reply:......troubles with editing...https://www.amazon.com/Radiowavz-Ant.../dp/B01M4NV336
Attached Images
Last edited by bead-boy; 05-05-2021 at 07:07 PM.Reason: .Century buzzbox that I learned on 40+ years ago (was Dad's)Crappy Century 110volt mig 70 amp pigeon pooper.Lincoln Idealarc TIG-300
Reply:Great post Don! I enjoyed reading it and admiring your craftsmanship.Miller Trailblazer Pro 350DMiller Suitcase MIGMiller Spectrum 2050Miller Syncrowave 250DXLincoln 210MP
Reply:
Originally Posted by Louie1961
I thought you said this was for a repeater installation? directional antennas like the ones you showed are typically not used for repeaters since they generally only radiate in one direction.
Reply:Thats some mighty fine machine work, well done.GeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun |
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发表于 2021-9-1 23:17:57