Drilling cast iron dumbell weights

[casstony]

Can the hole in cast iron weight plates be drilled to a slightly larger size?

The hole is about 29mm and would need to be drilled to fit a 31.75mm losmandy shaft.

[Astroman]

Might be better off getting someone with a metal lathe to open it up for you, the hole will be spot on then.. I don't think there is a problem with drilling or cutting.

[[1ponders]]

Tony, I've had two 7lb weights drilled out. They work fine on the Losmandy as long as you have someway to restrain them. eg between two other losmandy weights. You could sit it on the top of an existing weight but as the night progresses the DB weight might tend to roll around the center of gravity. :shrug:

I had mine done in a machine shop (not by me though) and drilling them out was np at all.

In the mean time you could try this.

http://www.iceinspace.com.au/forum/attachment_browse.php?a=3047
:D

[casstony]

Thanks for the quick replies guys.

Paul, I checked an old sledge hammer head in the shed - 28mm wide hole - oh well - good idea though. I'll see if a local shop will drill out my weights when they're open again. Any suggestion on what size hole I should ask for - I was thinking 33mm?

I picked up a used CW bar/plate for my alt/az DM6 mount (same as losmandy shaft) on the last US trip - since it's horizontal I don't need to worry about the weights moving.

[wasyoungonce]

Bintel is advertising Losmandy weights (https://www.bintelshop.com.au/welcome.htm).

A little expensive but not too badly priced.

edit:

ahh linky not worky...try page 2 of their mounts!

[[1ponders]]

Tony my sledge was too big as well. I just found a bolt long enough to pass through the head and screw into the losmandy shaft and put a large round washer on one side of the sledge head. Tightened it up onto the shaft and not a movement. ;)

[casstony]

Ah, I see - thanks for straightening that out:thumbsup:.

Wasyoung, those Bintel prices are just a little more than I'd like to pay, especially when compared to US prices.

[[1ponders]]

It really worked a treat Tony, it was on there for quite some time. Even after I bought a G11, I needed that other losmandy weight on it as well. So I left the sledge on there and used the drilled out weights. I also had some 60-70mm plugs cut out of 2" mild steel and had a threaded hole put into each. I used these as weighted clamps (each one about a kg or so) to hold the weights from moving. I may have some images somewhere. If I find any I'll post them

[pmrid]

Wow. Now that's what I call using your head.
Peter

[wasyoungonce]

Oh that is just hilarious! :rofl:Tears to my eyes!:lol:

[Barrykgerdes]

Drilling large holes in cast iron weights is not really a cheap action. A drill bit that size will cost the earth, then a drill to hold it another fortune. The drill probably won't get far before it will need sharpening.

It will be much cheaper to get a machine shop to bore it out on a lathe. I could do it but you are too far away. Although I am quite happy to bore out any weights that are brought to me. No charge.


Barry

[pmrid]

I've tackled this with 10Kg and 5Kg weights from a sports shop. The steel is amazingly hard and very tough on cutting bits. In the end, the bargdest task was getting the lathe chuck jaws to grip the weight firmly enough to be able to then drill out the hole. Managed to cut a shoulder on the side of the weight and got a grip sufficient to then carefully and slowly open the hole. By way of a locking mechanism, I put the weight in a a 45 deree angle and drilled and tapped a hole into the centre so it would take a suitable bolt to lock onto the shaft. The weights tehmselves were relatively cheap but the time and trouble involved in opening the hole made it a marginal solution at best. I'll throw up some images if anyone wants them.

Peter.

[Barrykgerdes]

Yes the toughness of some of that cast iron (old gas stoves etc) is very hard on cutting tools.

I can get 10" diam into a 4 jaw chuck, 7" into a 3 jaw. Anything larger would require a jig up to about 16"

Boring will require a tipped tool and done at a relatively low speed. I would also need to make a similar offset in the drill press to fit a locking screw.

Barry

[[1ponders]]

Tony, another option is you might want to contact Mick Pinner (http://www.iceinspace.com.au/forum/showthread.php?t=50888&highlight=losmandy). He was making counterweights for losmandy shafts. I'm not sure if he is still making them though.

[Barrykgerdes]

If I need a counterweight I prefer to make it out of steel. I go to the steel store and look for offcuts of 100-150 mm bar which you can purchase by weight. I have a power hacksaw which can cut off a chunk in about 10-20 minutes. This can then be cleaned up in the lathe to make a nice looking weight.

Ah! isn't it great to have a good workshop with all the necessary tools!

Incidently I do not make items to drawings (except my own). If you want something you need to bring the job around and I will work out the best way to do it.

Barry

[casstony]

Thanks for the comments guys - I've been leaving the machine shops alone over Xmas but it has occurred to me that I could just sandwich the weights between 2 pieces of plywood and drill a hole for the shaft in the plywood. Won't look pretty but it should work fine and I've got everything I need in the shed.

[mill]

I would use rubber sheet inbetween the weights so they wont slip at all, also rubber on the inside of the plywood would make slippage almost impossible.

[casstony]

Not a bad idea Martin - I have some old bicycle tube in the shed.

[Karls48]

It is much easier to make weights from the lead then using dumbbells. Couple of old car batteries will do. Drain the acid and leave battery upside down for week or so. Then smash the case with sledgehammer. Case plastic is pretty tough. Use gloves and safety goggles. Put the lead plates in old coffee tin and melt lead on BBQue. When it melts stir it and skim the dross. Pour the molten lead to the tin of size you want your weight to be. Let it cool and cut the tin with snips to get your weight out.
If you have access to small lathe it is easy to square it up and bore central hole. If not, you can use hand drill to drill 10mm hole and enlarge it with file. I have spray painted weight I made about two years ago with silver - $3 a can paint and it is still looking good.
When you melt lead don’t let it to get too hot. Lead melts at about 330 Deg. C, depending on purity. Around this temperature it is quite safe to work with as very little of poisonous fumes are emitted.

[casstony]

Not a bad idea Karl - I used lead stripped from cables to make sinkers as a kid. You could probably make a mold in the dirt with a piece of copper tubing the correct size in the centre to save having to drill out a hole, or punch a copper tube through a tin and have that sitting on dirt before pouring. What to do with the acid though?

As it is I've made this up - not pretty but it works and my 8yo had fun using the power tools to make it :) .

[Karls48]

I stored it in glass bottles in my shed and I will get rid of it when council will have a Chemicals collection day. Or I may use is to try anodising some aluminium bits and pieces.
Lead weights come up really nice, if you can square them on the lathe.

[spearo]

Hi
i too use weight lifting weights for my rig.

At first i found some fitted and some seemed a few microns up to a mm too small. Couldn't drill them out myself.

So i eventually just went to a weight training shop in Fyshwick (ACT) brought my Losmandy bar with me
explained to the very confused staff what i was doing and proceeded to try out a LARGE range of weights selecting only the ones that fitted the bar.

I sit them on top of the losmandy weight so I can adjust the balance etc.

cheers
frank

[Terry B]

The weights I bought had too big a hole for the bar on my EQ6. This made them wobble when the mount reversed. I just turned a sleeve in wood to make them a snug fit. Even without a lathe it wouldn't be hard to drill a bit of wood to size and saw/sand the outside down fit in the weight hole.

[Spanrz]

A great tool to enlarge holes, is to use a deburring tool. I use them at work, on particularly some really hard surfaces. It really loves mild steel :D
However, I know how hard Cast is, particularly when you try to cut it with an Oxy Set. Pain in the butt to heat up and cut.

Word of caution, Eye goggles are a must, as fine filaments of steel fly about.

http://www.sheffieldblades.com.au/burrs_countersinks_deburring.pdf