help with RAS

[marcros]

I have had a radial arm saw for a while, but have only just got around to getting it set up. I have a slight problem, but am stumped on how to rectify it. I cant remember what the saw was originally used for, but it was predominantly for a single thickness of material. It had various blades that have been sharpened, so it has seen some use, but I seem to remember it being a bit of a sideline operation to another business, rather than core so it shouldnt be worn out. i digress...

With everything on the saw locked, the arm can move slightly on the "piston". This is the silver part on the photograph. The arm of the saw and the piston itself rotate in the pistons sleeve at the bottom. This all moves by a degree or two- i have nothing to measure it with, but at 390mm, it is the difference of a kerf. Any ideas anybody- I guess that it shouldnt move at all. At full height, it doesnt seem to move hardly at all. that is why I mention that it may have been used at a single height for its life.

Any ideas what to look at?

 

[MMUK]

If it's been set at a single height it's possible the piston seal has dried out and you're losing piston pressure which is causing the free play.

 

[marcros]

having just looked in here, could it be item 4.5 http://www.drosera.f2s.com/RAS/DW1251.pdf on page11. It mentions about moving it from site to site- it certainly went from one place, to a shed, to my workshop where it has moved a couple of times. it has probably been lifted at some point by the arm, although i have been careful not to do so.

if it was a dry seal, would i also have play up and down (i dont), or not necessarily?

 

[condeesteso]

You don't mention the maker, but I had an Elu for a long time and had a similar problem on occasions. On the Elu (from memory, long gone now) the rise/fall column is locked at base (into casting), the top lever locks the arm in presets (90, 33, 45 degrees etc) but also allows any angle setting to lock. The indents for the presets get mucky and need a clean-out (minor strip down of the top rise/fall assembly) - or there is wear in the preset indent collar?
On my Elu that rise/fall column should not budge at all and is totally locked, so a look inside the top ass'y may well reveal the problem and it's quite likely to just need a good clean-out.
If yours is a DeWalt, then it's an Elu. DW bought Elu and kept some products totally unchanged, the RA saw was one of them, they just turned yellow later (but yours is green...).

 

[marcros]

Yes it is dewalt. Sounds very aimilar if not identical. I did look at that but the presets are solid enough- they lock the arm to the piston but the whole piston and arm seems to move together.

I will have another look later on. A minor strip and clean wouldn't do any harm anyway!

 

[powertools]

Adjustment 4.5 in those instructions is the problem care must be taken to ensure it is not too loose or to tight and the column and clamp need to be clean before adjusting. A tiny adjustment on any setting makes a big difference when the saw is fully extended.
Setting the machine up can be time consuming and annoying but once done they are great machines.

 

[marcros]

clean as in dust free I assume? Does it need any form of (dry?) lubricant on it.

Will it be obvious when it is not too loose or too tight? Just tight enough for there to be no slop?

Thanks Powertools, that might be this evening's job. Worth getting set up properly I think, even if it takes a while.

 

[powertools]

If it is too tight it will be hard to raise and lower the saw and may damage the internal thread in the column if it is too loose you will get the movement you have got.
If the saw has not been raised and lowered for some time you may have surface corrosion on the column where it has been in the clamp that will need cleaning I don't lubricate mine.
It is well worth taking the time to set it up well but with the time it takes I doubt if many were from when they were new.

 

[acewoodturner]

Hi Marcros
Get yourself a copy of the book on RAS's by Mr Sawdust. Following his instructions is relatively easy to adjust any of the dewalt or elu RAS's. There is a set sequence to doing this and if each one is carried out you will have an accurate machine. The main thing that can go wrong with these machine is that the ways can become worn if the previous owner has used it to do a repetitive job such as cut 100,000 lengths of 2 inch wood. That is unlikely though.
It can be a wee bit time consuming doing it for the first time as it will likely be out, most previous owners don't seem to be able to do this , or understand what each adjustment is for. It would also be worthwhile building a Mr Sawdust table as well as this adds to the overall accuracy of the whole set up.
Your model looks like one of the powershop range of the dewalts btw (possibly a 1251).

Mike

 

[marcros]

yes, it is a powershop 125. I dont think that there was any significant difference between that and the 1251.

The saw has the potential to be very useful, as long as i can get it to mitre cutting accuracy.

 

[Myfordman]

I don't find the DW series RAS accurate enough for quality mitre work by moving the head round.
Instead I would advocate the manufacture of a 45 degree jig to hold the work at 45 degrees to the standard fence leaving the main saw set to 90 degrees.

 

[condeesteso]

Ah yes, I recall mine was a 1251 (Elu but same as DW). Myfordman's point is v good, back in those days never thought of that but agree not close enough for framing (say).
I did a tweak on the table, mine had an mdf table on a steel base-frame. Nowhere near stable enough but a double layer of 15mm birch ply and some heftier metal under made a good difference. (Ply bonded dead flat of course.)
Still sounds to me like the actual column is moving/rotating slightly and I'm sure it must not at all. Then I recall a micro-adjust for the 90 degree, somewhere close to the rise/fall mechanism. Whatever the problem I don't think it'll be serious and I imagine minor spares would be easy to get off DeWalt.

 

[marcros]

I am a fan of getting machines to 90 degrees and avoiding touching them at all after that. On this one, I meant for box sides so it will be a straight cross cut with a tilted blade- easily set with the wixey digital angle gauge. And easily returned back to 90! I might make a couple of 45 jigs though.

I do have a table made from 2 pieces of 18mm ply (bonded flat!). It seems to be ok for now and the blade will just kiss it front and back- at least that adjustment is spot on!

 

[acewoodturner]

Hi Mark

Did you get your email ok

Mike

 

[marcros]

Hi Mark

Did you get your email ok

Mike

I havent seen it yet mike, but my iphone is painfully slow. i expect that it will be waiting for me at work in the morning.

Many thatnk.

Mark

 

[marcros]

well, one way or another, the problem seems to have been solved. It seems to have been a combination of things. I need to adjust a stop on the tilt of the blade, it is a fraction off, but it can be tilted to any angle without the stops, so isnt urgent.

do I need to grease bearings in the arm. I took the motor out and there was some (a little) black hardened gunk around the shiny surface of the bearings, and in the bit where they ran. It is now a bit stiffer than i would like as i pull through the cut.

 

[acewoodturner]

If I recall there are 3 or 4 bearings in the head. If there is 4 bearings the two on the rhs ( as you look from the front of the machine) will be on eccentric cams and can be moved out and in. If there are three I think that only one of them can be adjusted in or out. The bearings are sealed for life bearings and shouldn't be washed out or greased.
You can clean the gunk of the outside of the bearings with a little white spirit. The surface that the bearings come into contact is called the ways. This should be cleaned of all gunk as well. Make sure you are wearing work gloves to do this and not your bare hands. It doesn't take a lot to give you a nasty cut and then you have to clean off all the blood as well!!

Have some fun and take your time. The better job you do in tuning it up, the better the end result will be.

 

[marcros]

mine has 3 bearings. I will have a look at adjustment. Now I know how it comes apart, i am less daunted by it.

I cleaned the ways and the bearings with a dry cotton t shirt- it came off easily enough. the bearings span easily enough, and there were no sticking points/resistance points along the ways. I put them back dry because i thought that oil wasn't good for normal bearings and would be messy, and i don't possess any grease!

How easily should it be to pull through a cut- i assume it should require some effort, but is it a glide, like playing snooker or like bowling?

 

[acewoodturner]

It should be a glide with a little effort. If it was too tight it kind of 'stutters' through if you get my drift! Just don't grease the ways, they should be dry.

 

[marcros]

think it is a touch tight then. just found the relevant bit in Mr Sawdust. I had printed off the bit afterwards to work through. at least i wont get covered in grease adjusting them!