mashtroy/ warc 220 bush

hi

hope some one can help, i have a mashtroy (warco) 220 lathe and the brass bush on the topslide has worn out, it looks like a acme type thread and is 10mm or 3/8 dia and the tpi is 18. Does any one know of a tap that is suitable to make a new bush or maybe someone knows of a replacement. Warco has been no help and i have emailed the original company who were helpfull but so far can not identify my lathe.

Also any suggestion as to why this should wear out so quickly, my lathe is 15 years old but has had very little use, i know the bush is quite small but is this a common problem. any help greatly appreciated.

thanks

Dave

Edited By Dave Owen on 07/01/2015 17:38:23

Hi Dave, don't know if there is a suitable tap readily available, but I believe the Mastroy version is C210T. Below are scans of the carriage assembly with ID numbers which may help you source parts.

Regards Nick.

Hi Dave,

I had exactly the same problem on my 220, and as you found Warco were of no use (in fact they totally ignored me).

I ended up making a tap to suit which kind of worked well enough to solve the problem, but I will make another better one next time.

Perhaps I should invest in a tap as this is, or will be a common failure in the future.

Regards, Chris

As you say the thread is acme this is presumably the feedscrew nut. 18 tpi would be useless as an imperial feedscrew as the pitch is not a useful subdivision of an inch. Almost certainly therefore metric (as my Warco 220 was). Try counting the threads against a mm rule, you should get a more sensible answer. Then you would need a suitable acme metric tap, maybe Tracy Tools may have one. The most likely pitch is actually 2 mm, but that would be more like 12.7 tpi. I can't remember actually what it was, actually I prefer to forget that lathe...

hard to say why it has worn, but brass is not a good material to use for this purpose. If you made another one a bit of decent bronze would be better. What do you mean by worn out anyway? Are the threads stripped, or is there just a lot of play?

Hi Guys

thanks for the replies, it looks like a common fault on this lathe. John i will re count the threads in the morning and re post, The thread are nearly gone it started with a lot of play and quickly ended up as stripped. i think part of the problem is over tightening the 4 way tool post, it seems to put extra pressure on the top slide. 12.7 TPI or there abouts would make more sense as there are 10 tPI taps available.

Chris, i plan to make at least 2 replacements as they will wear, at my local engineering club today (pembrokeshire model engineers) google it for web site. It was suggested to drill out the hole in the top slide to make a larger dia to allow a larger bush, something to think about.

thanks again

Dave

p.s. if you do look at our web site my engine is the winson 1400 tank

Hi Dave,

Thread is 10mm x 1.5mm pitch trapezoidal IIRC. As you say, tightening the toolpost is a major cause as it forces the topslide to bend, tightening the gibs up. A very thin shim washer between toolpost and topslide would help to reduce that.

Regards,

Chris

Agree with the 1.5mm pitch. Also, the lathe is indeed the Mashstroy C210t.

My 220 is 20 years old but as I seldom use the topslide this hasn't been a problem for me. But I do agree that it can be very tight. Might I suggest that possibly a balancing tool on the opposite side of the 4-way toolpost will help.

Good luck with your repair, and please let us know how you get on with it.

Regards,

Peter G. Shaw

Hi Chris

many thanks for the info, any idea where to get a tap that size? i have checked online and there are some from the USA but very silly money,some one suggested a 3/8 x 10 tpi is very close. Any thoughts.

It also seems a good idea to shim the toolpost, when it is tight it more or less locks the whole topslide.

thanks again

Dave

ps i can get a 10x 2 trapezoidal tap in this country, do you think that may work?

Dave,

If you use a 10 x 2 tap, presuming that the 2 refers to the pitch, you will not be able to use the graduations on the handle.

Just thinking a bit more about the tightening up of the topslide. I normally use mine with the tool set more or less over the leading edge of the cross-slide since this puts the cutting forces over the cross-slide which is where they are supposed to be. The only occasion where I have needed to advance the top-slide has been when cutting close up to the mandrel when using a direct collet. In this instance, the saddle becomes hard up against the headstock and thus to get that last 30mm or so, I have to use the top-slide. Even so, my method is to adjust the positioning of the saddle and topslide such that tool has just traversed the required cut when the saddle contacts the headstock. Maybe a couple of millimetres past. This adjustment is done with the mandrel stationary hence the top-slide positioning can be done with the tool clamp slack. Indeed, when boring I have set topslide and saddle with the tool slack, pushing the tool into the required position before tightening the tool clamps. Thus, I find there is little need to turn the topslide handle under load.

Of course, if you are into turning tapers with the topslide, then that is a different kettle of fish. Here, I think the idea of a balancing tool on the opposite side to the cutting tool will help.

Final thought is that is it actually necessary to have the tool clamps that tight? I have a suspicion that I tend to run with the tool clamps not exactly slack, but tending that way. And yes, I have had the occasional tool slip, but nothing absolutely detrimental.

Regards,

Peter G. Shaw

Is this of any use? **LINK**

hi bob

that looks the business, will order asap, Pete overtightening the tool post is a problem, i have just made a shim and it made little difference, maybe too thin.|

Dave,

Having replaced the feed nut I slackened off the gib strips, then tightened the toolpost fully. Having done that, the gibs were then adjusted to give a smooth movement. Not an ideal solution as you are now running with a bent topslide, however, since you will not be attempting to use the lathe with a loose toolpost, it does make it workable.

Like Peter I rarely use the topslide these days, since the lathe is only rarely used while others are set up on long jobs

Chris