Not the cheapest route, although that depends on the shop and the cost
of the steel plate, but starting over with a set of tolerances up front
in thousandths of an inch permissible, or fractions like 1/64th? should
give the strongest, safest, and most accurate base. It's really the
best all around route. Many shop tolerances are 1/8th inch unless
otherwise specified. If they know the bolts are already set in
concrete, they will know the need for close tolerances.
I really messed up on my tower base for the LM-470. I used to be able
to take measurements like that and come out really close, but this one
had the top hole on one ear almost far enough to drill a new hole. I'm
going to have to start hiring more of this stuff done. Measuring once
and cutting twice is no longer sufficient <:-) Had I remeasured before
each additional tack weld, I'd most likely been OK. As I can make a new
ear in less than an hour, cut the old one off. bolt the new one on and
then weld it to the base in another hour or so, I may just go that route.
73 and good luck on this one.
Roger (K8RI)
On 9/8/2015 3:48 PM, Rich Hallman - N7TR wrote:
I've decided to have another machine shop build me a new plate. Trying to fix
this one was going to be an issue on several fronts.
Thanks again for all the info and ideas... Rich
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Rich
Hallman - N7TR
Sent: Monday, September 07, 2015 3:38 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Grinding hole in thick steel plate?
Thanks for all the ideas so far. If I need to I may take the plate to a
fabricator and see if they can mill these to the correct locations, but I would
rather do this at my house for now. For those who asked...The plate is 3/4
inch thick steel plate. The holes are 1 1/4 in diameter for the 1 1/8 inch
all-thread anchor bolts.
I have purchased and should be here tomorrow...the below Die Grinder as well as
several 1 1/2 inch diameter 1 inch long carbide burr bits. These are double
cut. Would a single cut be better for this need?
http://www.amazon.com/gp/product/B00FDLB9OC?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s01
http://www.amazon.com/gp/product/B00ECMMOW4?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
I wonder if I need to get a 3/4 inch or 1 inch diameter carbide burr bit?
Thanks....
Rich
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Rich
Hallman - N7TR
Sent: Monday, September 07, 2015 11:33 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Grinding hole in thick steel plate?
I had a ¾ inch steel plate made up that will be used to retrofit a HDX589 base
foundation to a HDX572 base. After giving both bases to the machine shop and asking
them to make sure all of the holes are exactly the same location as the base, some of the
holes are 1/8 to ¼ inch off. I had a major issue with this machine shop so I will
not take it back for now.
I wanted to see what others have done to grind out holes in thick steel plate.
I was looking at the Carbide Burr bits and getting a ¾ inch burr bit to see if
that would grid enough from the hole so it would then fit the bases.
The holes are pretty close....so I thought grinding them out would be the best
solution for now.
Any thoughts?
Thanks....Rich
Rich N7TR
ex KI3V, N3AMK, WB3JOV
www.n7tr.com<http://www.n7tr.com>
http://www.qrz.com/db/N7TR
Telnet: dxc.n7tr.com N7TR DXCluster
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73
Roger (K8RI)
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