Help with accurate milling of arrow testing machine
(posted by Susan Iwanek)
Trustee Steve Bloor, the chairman of the Shropshire panel, has been discussing with the new Paralympics coach at UK Archery how Remap can help disabled archers. One particular problem they have, with which they would very much like Remap’s help, is with adapting a machine they have to test arrows. The machine is shown in the two pictures below (apologies for the poor quality of one of them).
Each arrow to be tested is placed in the machine, which then places a weight on it to create stresses and turns it. A sensor monitors the ‘wobble’, enabling defective arrows to be eliminated.
The problem with the machine is that it takes only one length of arrow and arrows come in several different lengths. They need it to be adapted so that the pillars that hold the arrow can be moved along the bed while retaining the integrity and accuracy along with the mechanism for rotating the arrow.
The Shropshire panel does not have a milling machine capable of work this accurate. Do any other members feel they have the capacity to make these alterations to the machine? UK Archery are prepared to deliver it anywhere in the country so location is not an issue.
If you feel you can help please contact Steve Bloor direct at steve@sbloor.freeserve.co.uk or respond in comment box below.
- Skills involved:
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Many thanks
Could i please have your email address
Steve
I note from the illustration that the test unit seems to have been derived from the headstock of a variable speed mini lathe with some attachments. It is possible to obtain these machines in 14,16 and 20 inch bed lengths. So with a suitable jig mounted on the cross slide it would be possible to obtain an accurate movement for different lengths of arrow (the cross slide is power driven by the lead screw if necessary).
These machines are also relatively easy to move by one or two people unlike conventional lathes which normally require specialized lifting gear. If further extensions are required then constructing a support jig bolted to the RHS of the cross slide in the form of a travelling steady should enable continuing accuracy.
I perceive that the original unit was constructed by Sheffield University to make it a light weight machine but in doing so this has removed the original accuracy causing future problems.
I am in the Southend & District Panel and have used these mini lathes in various forms for a number of years.
I agree with Mark Mercer that more clarity is needed on what is required. I see that that Sheffield University already have a rig manufactured, but to my mind any `lathe type machine ` has to have a bed with a continous longtidinal location i.e vee slide so that all components – headstock/drive unit plus any other attachments like `tailstock` or location holder are all attached to the same datum. Also any additional brackets must be `clamped` to the bed and caple of being adjusted for position and locked. A lathe tailstock is an obvious example. The pictures appear to show a bolted attachment which is fixed, but there are no obvious location guides – keyway, dowels or sides of base frame.
I notice that a lower secondry shaft exists with a belt up to the arrow, but it is not clear how this is driven. I know it is perhaps too late to comment, but a more workman like job could have been achieved using an old Myford 40″ lathe bed as the base and machining any slides to suit the frame profile. The existing belt drive could have been updated to use the new variable speed drive shown.
For portability an extension piece would seem a viable option. As Mark Mercer observes: is the alignment critical with the bed of the exisisting unit. If so could have adjusting feet. Assume would use test bar to align or laser equipment.
The Essex North East panel (Colchester) have faciities to assist.
I have a Bridgeport milling machine but cannot tell from the pictures and description what it would be required to do. Do they want the bed milling out to make a lathe like slide or what?
It is difficult to guess what actually ‘grips’ the arrow to cause rotation. Is there a belt or rubber rollers or something?
Are they spinning the arrows at speed to test for whip effects? Or does the arrow just turn at a slow speed? If the latter one would have expect it to be rotated by hand.
Does there need to be a bed extension or is it OK for the longest arrows and only in need of adjustment for shorter ones?
Since the measurement is relative round the centre it would seem that ‘accuracy’ between the end supports is not critical.
Decent pictures (with an arrow in place) and clearer description would be helpful.
What is the basic bed length
I gather they require extra pillar fixing locations between the current positions
In the absence of a closer panel, I’m willing to offer my services
We are Carlisle & District Panel
My location : Langholm DG13
Hi Steve,
I sent you an e-mail a couple of days ago from my son’s business address. Just in case it didn’t arrive here’s a repeat.
kilncroft@hotmail.com
Kind regards
Jack Rae
Chairman of Carlisle panel (unless I get voted off this coming Friday 🙂 )